Title of Invention	A PROCESS FOR THE PRODUCTION OF HIGH-OCTANE GASOLINE FROM STRAIGHT RUN LIGHT NAPHTHA ON PT CONTAINING HZSM-5 MOLECULAR SIEVE CATALYST
Abstract	A process for the production of high-octane gasoline from straight run light naphtha containing C6 to C8 range paraffins and naphthenes over a Pt containing HZSM-5 molecular sieve catalyst The present invention relates to a process for the production of high-octane gasoline from straight run light naphtha on Pt containing HZSM-5 molecular sieve catalyst. The preparation of the catalyst for the process does not involve the steps of steaming and acid leaching before the actual catalytic application. The mentioned catalyst is environmentally friendly as the preparation does not involve the use of hazardous mineral acids, viz., HCl, HNO3 etc. The process of the present invention converts all types of hydrocarbon components present in the light naphtha feed viz. Paraffins, isoparaffins, naphthenes and benzene into aromatic hydrocarbons, isoparaffinic and LPG, at high selectivity with single catalyst system. Light naphtha, which does not have potential use as conventional reformer feed stock, can be used as a feed in this process.

Title of Invention

A PROCESS FOR THE PRODUCTION OF HIGH-OCTANE GASOLINE FROM STRAIGHT RUN LIGHT NAPHTHA ON PT CONTAINING HZSM-5 MOLECULAR SIEVE CATALYST

Abstract

A process for the production of high-octane gasoline from straight run light naphtha containing C6 to C8 range paraffins and naphthenes over a Pt containing HZSM-5 molecular sieve catalyst The present invention relates to a process for the production of high-octane gasoline from straight run light naphtha on Pt containing HZSM-5 molecular sieve catalyst. The preparation of the catalyst for the process does not involve the steps of steaming and acid leaching before the actual catalytic application. The mentioned catalyst is environmentally friendly as the preparation does not involve the use of hazardous mineral acids, viz., HCl, HNO3 etc. The process of the present invention converts all types of hydrocarbon components present in the light naphtha feed viz. Paraffins, isoparaffins, naphthenes and benzene into aromatic hydrocarbons, isoparaffinic and LPG, at high selectivity with single catalyst system. Light naphtha, which does not have potential use as conventional reformer feed stock, can be used as a feed in this process.

Full Text	The present invention relates to a process for the production of high-octane gasoline from straight run light naphtha on Pt containing HZSM-5 molecular sieve catalyst. More particularly the present invention relates to a process for the utilization of straight run light naphtha feedstock available from various refineries, into value added aromatics with low amounts of benzene which can be used as blending stocks for improvement of octane number in gasoline fuel. In addition to highoctane gasoline liquid product, some amounts of gas by-product are also obtained which can be used as domestic fuel (LPG). The fast growing automobile population as well as increasing pressure from environmental legislators has resulted in demand for good quality gasoline in the country. The focal point for the improvement of gasoline quality, at present is centered around benzene content of 5% (V/V) with already lead free gasoline available in India (Ref. Report of Sub-group on the Refining for IXth plan 1996). It is stated that some of the refiners will be unable to meet the specification of benzene leading to gasoline production loss. To address the benzene problem in gasoline it is suggested to increase IBP of reformer feed by adjusting naphtha splitter cut point which leads to substantial loss in gasoline production volume and increased quantities of light naphtha. As a result increasing interest is shown in the development of new catalysts and processes, which allow production of gasoline with sufficiently high octane numbers, making use of unconventional low value feed stock such as light naphtha into standard gasoline production. In addition to this, the demand for LPG is also growing much faster in India at growth rate of 12 to 13 percent per year. The corresponding deficit of LPG in 2000-01 is 4 million tons and expected to increase up to 7.8 million tons by the year 2010-2011 (Sundar Rajan Committee Report on Hydrocarbon perspective 1996, Ref LPG News of India, March'96, p 17). tight naphtha is one of the least viable petroleum feed stocks treated today. Projected production of straight run light naphtha cut (IBP-130) other than catalytic reforming feed in India indicates 1-1.25 MMTPA (million metric tons) of light naphtha is available from various refineries in 1996-97. Light naphtha mainly contains Cs and C6 hydrocarbons (30 to 40 wt%) depending upon the source. Due to high percentage of n-paraffins in light naphtha it has lower research octane number (RON) and high RVP (Reid Vapour Pressure) due to nand i-pentanes, hence it cannot be used directly for gasoline blending. Thus, the conversion of light naphtha into other petroleum and petrochemical products gains significance in this scenario. Conventionally, gasoline is being produced from the Catalytic reforming process of naphtha and Fluid catalytic cracking units from various refineries. The indigenous gasoline production by refineries with low benzene content will be inadequate to meet the demands in future like at present. The catalyst used for reforming process is monometallic Pt/Al2O3 or Pt-Re/Al2O3 bimetallic catalyst. Although these processes are used all over the world, there are number of limitations in the use of these catalysts. The conventional catalyst is not effective in promoting aromatization of light naphtha rich in C5 hydrocarbons. The catalyst is also not very effective in promoting the aromatization of straight chain paraffins such as n-hexane and n-heptane present in the feed that remain unconverted. On the other hand, LPG production either from refineries or from gas fields is not enough to meet the demands. The import situation is also not encouraging, as only a few private entrepreneurs have actually created facilities for import market. Therefore the increasing demand for good quality gasoline and increasing gap between LPG deficit and import capacity also indicates the need to develop novel processes for the production of gasoline as well as LPG from cheaply available feed stocks, viz., light naphtha. There are reports in the literature on the conversion of these straight chain paraffins into aromatics, using zeolites and metal-doped zeolites as catalyst. Reference may be made to a process developed by Mobil researchers (Ind. Eng. Chem. Process. Design Dev., 25 (1986) wherein the preparation of aromatics from variety of feedstock such as pyrolysis gasoline, unsaturated gases from catalytic cracker, paraffinic naphtha and LPG have been described. Another reference may be made to (Patent of Russia Federation No 1141704, Appl. 17.06.1983) wherein method of producing gasoline fractions from gas condensate over HZSM-5 catalyst has described. The limitation of this process is that it utilizes long range naphtha (80-180°C) which is also a feedstock for catalytic reforming unit. Another reference may be made to (Hydrocarbon Processing Sept., 1989 p 72) wherein a process developed jointly by UOP Inc. and British Petroleum, based on gallium doped zeolite catalyst has been reported. In this process LPG was converted into BTX aromatics and the process has been demonstrated in a largescale pilot plant of the British Petroleum Grangemouth refinery in Scotland. Yet another reference may be made to (US patent 5,026,938 dated 25th June' 1991) wherein a process for converting a gaseous feed stock containing C3-C5 paraffins into aromatics hydrocarbons by contacting the feed with gallosilicate molecular sieve catalyst has been described. The draw back of all these processes is that these are mainly related to the production of aromatics from paraffins of €3 - Cs range which are in high demand as LPG in India. Still another reference may be made to US patent 5,125, 415, dated June 1992 wherein the use of Pt-Sn-ZSM 5 catalyst for the production of mono-alkyl aromatics from Cg n-paraffins containing feed stocks has been described. The limitation of the above process is production of xylenes from Ca-Cg hydrocarbons. Still another reference may be made to (IPA No. 010/DEL/2001 dated 05/01/2001) wherein a process for the conversion of natural gas liquid (NGL) into liquefied petroleum gas (LPG) and high-octane gasoline over modified ZSM-5 zeolite has been reported. The limitation of above process is that zeolite catalyst was modified by steaming method and it produces more LPG (55 wt%) than aromatics (22wt%). Still another reference may be made to (IPA No. 2627/DEL/96-dated 29/11/96) wherein a process for the preparation of a novel modified ZSM-5 zeolite has been reported. In this process zeolite catalyst was modified by steaming method followed by acid leaching to remove the extra framework alumina. The limitations of the above process are firstly formation of high quantity (8-12 wt %) of dry gas (Q+C2) during the n- heptane conversion which will be a loss to the economy of the process. Secondly the preparation of ZSM-5 catalyst in this process involves acid leaching step which involves the use of hazardous mineral acids viz. HC1. The main object of the present invention is to provide a process for the production of high-octane gasoline from straight run light naphtha on platinum containing HZSM-5 molecular sieve catalyst, which obviates the drawbacks as detailed above. Another object of the present invention is to provide a process for the conversion of light naphtha into high octane low benzene content unleaded gasoline as a blender to boost the octane number along with LPG as by product by using a catalyst system containing platinum supported ZSM-5 zeolite composite. Another object of the present invention is to provide a process for the preparation of platinum metal modified ZSM-5 zeolite catalyst by impregnation method with out acidity modification by steaming and acid leaching steps. Yet another object of the invention is to provide a process, which utilizes the straight run light naphtha containing up to 35 hydrocarbon components for the production of high-octane gasoline unlike the other existing processes. Still another object of invention is to convert C5 -C7 paraffinic and C6- C8 naphthenic components efficiently to produce high-octane gasoline. Another object of invention is to provide a process that produces in addition to n-paraffinic and naphthenic components, isoparaffins; benzene and other aromatics present in the feed also can be effectively converted to give high octane gasoline with low benzene content and LPG. Accordingly the present invention provides a process for the production of high-octane gasoline from straight run light naphtha containing C6 to C8 range paraffins and naphthenes on a Pt containing HZSM-5 molecular sieve catalyst which comprises: (i) impregnating 0.1-2.0 wt% of Pt from tetramine platinum chloride on a HZSM-5 zeolite extrudate, (ii) drying the above said zeolite extrudate at a temperature of 110°C for a period of 10- 12 hrs followed by calcinations at a temperature of 400-600°C for a period of 1-4 hrs in static air, (iii)loading the above said treated Pt impregnated zeolite extrudates in high pressure reactor and reducing it by passing hydrogen for a period of 2-5 hours at a temperature of 400-500°C and at a flow rate of 8-12 1/h into the reactor, (iv) cooling the above said Pt impregnated zeolite bed to a temperature of about 300°C under nitrogen atmosphere and increasing thereafter further bed temperature to 300- 600°C, (v) passing light naphtha through the above said bed at a weight hourly space velocity ranging from 1 to 8 hrs' and at a pressure in the range of 1 to 25 kg/cm2 and in the absence of nitrogen to obtain a mixture of high octane gasoline and LPG and separating the gasoline from the mixture by conventional method.. In an embodiment of the invention the light naphtha feedstock comprises light naphtha containing C6 to C8 range paraffins and naphthenes. In another embodiment of the invention the reaction temperature is in the range of 400-500°C. In yet another embodiment of the invention the pressure is in the range of 1-10 kg/cm2. In another embodiment of the invention the weight hourly space velocity of light naphta is in the range of 2-8hrs-1. In another embodiment of the invention the Research Octane Number (RON) of straight light naphtha fraction is increased from 64 to 97 in the product with gain of 34 units. In another embodiment of the invention the platinum impregnated ZSM- 5 zeolite composite used is prepared by incipient wetness method. In another embodiment of the invention the catalyst used is regenerated by oxidative combustion. In another embodiment of the invention the total amount of platinum metal added into HZSM-5 molecular sieve is in the range of 0.1 to 1.1 wt%. In another embodiment of the invention the catalyst used results in the reduction of the sulfur content in light naphtha feed stock from 50 ppm level sulfur to 10 ppm level sulfur in the product. In still another embodiment of the present invention the process conditions viz. pressure can be varied to in order to increase the aromatic content and decrease the LPG in product mixture advantageously. In the present invention, preparation of the catalyst for the process does not involve the steps of steaming and acid leaching before the actual catalytic application. The mentioned catalyst is environmentally friendly as the preparation does not involve the use of hazardous mineral acids, viz., HC1, HNO3 etc. The detailed steps of the process are: About 18cc of the catalyst (13 g) in extruded form of 1.5 to 2 mm diameter is loaded in a fixed bed, down flow, high pressure reactor. Before the test runs, the catalyst is reduced at 450°C with H2 gas for 4 hours with flow rate of 10 1/h. It is cooled down to 300°C in N2 flow and heated again to desired reaction temperature. The light naphtha is pumped by plunger type feed pump and N2 flow was stopped totally. Reactor effluents are cooled before being fed to highpressure separator. The vapors from separator are purged, while the liquid phase is sent to stabilizer column. Regeneration of the deactivated catalyst in reactor is carried out by conventional procedure using air and nitrogen mixture. The liquid product is analyzed using a gas Chromatograph fitted with Tetra Cyano Ethoxy Propionitrile column and FID detector. The gaseous products are analyzed using Squalane column. In the present invention, the process conditions have been optimized for the controlled d+ C2 (dry gas) yield, which is not desired in the gasoline process. In order to reduce the duration of regeneration of the catalyst thereby to improve the catalyst life against the coke lay down, 0.4 wt% of platinum metal is doped on HZSM-5 catalyst. In the present invention, the novel process developed can operate for maximization of LPG too by simply altering the process parameters. The catalyst used in present process is a novel platinum supported HZSM-5 zeolite in which parent ZSM-5 zeolite composite was procured from Zeolyst international (Lot No. 1822-43). The zeolite to binder ratio of HZSM-5 extrudates were 80:20. These extrudates were impregnated with 0.4 wt% of Pt from tetraamine platinum chloride (Aldrich) solution. These extrudates were oven dried at 110°C for 12 hrs and then processed to calcination at 500°C for 3hrs in static air. The Physico-chemical properties of the zeolite catalyst are as follows: Characteristics of Parent HZSM-5: Si-Al ratio (SAR):100; XRD Crystallinity:99%; Catalyst: Pt/HZSM-5; Shape: Cylindrical form; Diameter: 1.5-2.0mm; Bulk Density: 0.7-0.75 gm/cc; BET Surface Area: 3 5 0-400 m2/g The composition of straight run light naphtha used in this process has been analyzed by GC is shown below. Light naphtha Feed Composition (wt %): (Figure Removed) The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. EXAMPLE -1 This example describes the characteristics of the high-octane gasoline liquid product and LPG obtained in the present process from the light naphtha feed stock. The yields of individual product components that can be obtained in this process are given. The analysis is based on the GC fitted with Tetra Cyano Ethoxy Propionitrate column and FID detector. Table -1 Characteristics of Feed and Liquid Products of this process Process conditions: Catalyst: Pt/HZSM-5; Feed: light naphtha of Numaligharh refinery Reaction Temperature: 450°C; Pressure: 3kg/cm2; WHSV: 6hr"!; TOS: 24 hrs; Reactor: Micro Reactor of 25 gm-catalyst capacity. Component Light naphtha Feed (wt%) Liquid Dry Gas LPG(C3+C4) Total Paraffins* Total Aromatics Benzene content Density of the Liquid (g/cc) Research Octane No. (RON) Sulphur (ppm) RVP of liquid (kPa at 38°C) Existent gum (g/m3) Potential gum (g/m3) Distillation a.Initial Boiling Point(°C) b.Recovery up to 70°C(%vol) c.recovery up to 100°C d.recovery up to 1 80 C e.Final boiling point(°C) f.Residue (%vol) (Figure Removed) excluding C6-Cg naphthenes of 46wt% This table shows the conversion of light naphtha feed stock having RON of 64 into aromatics rich (60%) liquid product with low benzene content having a to RON 97.4. The novelty of this process is that 85 wt% of high-octane gasoline was produced from low value feedstock, which could also meet the future environmental regulations on gasoline in terms of low benzene content and low sulphur level. EXAMPLE - 2 This example illustrates the results of effect of temperature on product distribution of aromatics (BTX) in liquid product, LPG and dry gas. The gaseous and liquid products were analyzed by same method, which was mentioned in example 1. Table - 2 Effect of Temperature on Product Yields Process conditions: Catalyst: Pt/HZSM-5; Feed: light naphtha Pressure: 20 kg/cm2; WHSV: 6 hr'1; TOS: 24 hrs Temperature ( C) Ex-reactor yield (Wt% based on the feed) (Table Removed) Table-2 shows that the yield of aromatics (BTX) increases with increase of temperature and the optimum temperature for the present process was chosen as 450°C due to formation of less coke during reaction. EXAMPLE - 3 This example includes the results of effect of pressure on the yields and composition of aromatics and LPG. The product analysis presented in table-3. Table - 3 Effect of Pressure on Product Yields Process conditions: Catalyst: Pt/HZSM-5; Feed: Straight run light naphtha Temperature: 450°C; WHSV: 6 hr'1; TOS: 24 hrs Pressure (kg/cm2) 20 3 Ex-Reactor Yields (Wt % based on the feed) (Table Removed) The experimental results reported in table-3 shows that the decrease of pressure increases the BTX production with decrease in yields of LPG. The optimum pressure for this process was fixed at 3 Kg/cm2 due to more aromatic formation. EXAMPLE - 4 This example illustrates the results of effect of weight hourly space velocity on the yield and composition of high-octane gasoline and LPG. The product analysis presented in table-4. Table - 4 Effect of Weight Hourly Space Velocity on Product Yields Process conditions: Catalyst: Pt/HZSM-5; Feed: Straight run light naphtha Temperature: 450° C; Pressure: 3 kg/cm2; TOS: 24 hrs WHSV (hr"1) o \ 0 2 X f Ex-Reactor Yields (W t% based on the feed) Dry gas 1.0 1.3 LPG (Table Removed) From the above table-4, it is shown that the increase of WHSV to 6 decreases the LPG yield and increases aromatic yields with similar dry gas yields. EXAMPLE - 5 This example illustrates the effect of run length on the product yield viz. BTX, LPG and their composition. In the run length of 24 hrs, the product was analyzed at various intervals and results are presented in table-5. Table - 5 Catalyst Stability Studies Process conditions: Catalyst: Pt/HZSM-5; Feed: Straight run light naphtha; Temperature: 450°C; WHSV: 6.0 hrs'1; Pressure: 3 Kg/cm2 Time (hrs on - stream) 8 16 24 Ex-Reactor Yields (Wt% based on the feed) (Table Removed) Table-5 shows consistent yield patterns of BTX in Liquid product and decrease in yields of LPG at WHSV of 6 hrs"1 persists over the run length of 24 hrs. EXAMPLE - 6 This example explains the effect of catalyst regeneration on the product yields in the present process of high-octane gasoline production from light naphtha. The products yield patterns before and after the regeneration was given in the table-6. Table - 6 Reproducibility of the Ex-reactor yields before and after the Regeneration Process Process conditions: Catalyst: Pt/HZSM-5; Feed: light naphtha; TOS: 24hrs Reaction Temperature: 400°C; Pressure: 20 kg/cm2; WHSV: 6 hr ~' Process Performance Before RegenerationAfter Regeneration Ex-Reactor Yields (Wt %based on the feed) Table-6 shows the similar yield patterns of BTX aromatics in liquid product and LPG in both before and after the regeneration of the catalyst indicating the complete removal of coke lay down during the reaction. The main advantages of the present invention are: l.The process of the present invention converts all types of hydrocarbon components present in the light naphtha feed viz. Paraffins, isoparaffins, naphthenes and benzene into aromatic hydrocarbons, isoparaffmic and LPG, at high selectivity with single catalyst system. 2.Light naphtha, which does not have potential use as conventional reformer feed stock, can be used as a feed in this process. 3.The catalyst used in this process is ecofriendly and it does not involve the acid leaching with hazardous mineral acids such as HC1 during preparation. 4.The catalyst used in this process reduces dry gas yields to 2 wt% with increase of high-octane liquid product and thereby improves the economics of this process. 5.LPG, which is a by-product in the present process, can meet the industrial and domestic demands. 6.The process does not require hydrogen during feed cut in. 7.The process also does not require use of corrosive organic chloride additives. 8.The high-octane liquid a major product obtained in the process can be used as a gasoline blender to boost octane number. 9.This process is economically profitable and depending on the capital investment the pay back period will be 1.5 to 3 years. lO.The process maintains constant production of high-octane gasoline pool by utilization of light naphtha from reformate. 11. The catalyst can desulphurize the synthesized gasoline to lOppm from SOppm of light naphtha feed. We claim: 1. A process for the production of high-octane gasoline from straight run light naphtha containing C6 to C8 range paraffins and naphthenes on a Pt containing HZSM-5 molecular sieve catalyst which comprises (i) impregnating 0.1-2.0 wt% of Pt from tetramine platinum chloride on a HZSM-5 zeolite extrudate, (ii) drying the above said zeolite extrudate at a temperature of 110°C for a period of 10-12 hrs followed by calcinations at a temperature of 400-600°C for a period of 1-4 hrs in static air, (iii)loading the above said treated Pt impregnated zeolite extrudates in high pressure reactor and reducing it by passing hydrogen for a period of 2-5 hours at a temperature of 400-500°C and at a flow rate of 8-12 1/h into the reactor, (iv)cooling the above said Pt impregnated zeolite bed to a temperature of about 300°C under nitrogen atmosphere and increasing thereafter further bed temperature to 300-600°C, (v) passing light naphtha through the above said bed at a weight hourly space velocity ranging from 1 to 8 hrs ' and at a pressure in the range of 1 to 25 kg/cm2 and in the absence of nitrogen to obtain a mixture of high octane gasoline and LPG and separating the gasoline from the mixture by conventional method.. 2. A process as claimed in claim 1, wherein the reaction temperature used is preferably in the range of 400-500°C. 3. A process as claimed in claim 1, wherein the reaction pressure used is preferably in the range of 1 -10 kg/cm2. 4. A process as claimed in claim 1, wherein the weight hourly space velocity of light naphta is preferably in the range of 2-8hrs '. 5. A process as claimed in claims 1 to 4, wherein the Research Octane Number (RON) of straight light naphtha fraction is increased from 64 to 97 in the product with gain of 34 units. 6. A process as claimed in claims 1 to5, wherein the platinum impregnated ZSM- 5 zeolite composite used is prepared by incipient wetness method. 7. A process as claimed in claims 1 to 6, wherein the catalyst used is regenerated by oxidative combustion. 8. A process as claimed in claim 1 to 7, wherein the total amount of platinum metal added into HZSM-5 molecular sieve is in the range of 0.1 to 1.1 wt%. 9. A process as claimed in claims 1 to 8, wherein the catalyst used results in the reduction of the sulfur content in light naphtha feed stock from 50 ppm level sulfur to 10 ppm level sulfur in the product. 10. A process as claimed in claims 1 to 9,wherein the pressure is varied in order to increase the aromatic content and decrease the LPG in product mixture. 11. A process for the production of high-octane gasoline from straight run light naphtha on a Pt containing HZSM-5 molecular sieve catalyst substantially as herein described with reference to the examples accompanying this specification.

Full Text

The present invention relates to a process for the production of high-octane
gasoline from straight run light naphtha on Pt containing HZSM-5 molecular
sieve catalyst.
More particularly the present invention relates to a process for the utilization of
straight run light naphtha feedstock available from various refineries, into value
added aromatics with low amounts of benzene which can be used as blending
stocks for improvement of octane number in gasoline fuel. In addition to highoctane
gasoline liquid product, some amounts of gas by-product are also
obtained which can be used as domestic fuel (LPG).
The fast growing automobile population as well as increasing pressure from
environmental legislators has resulted in demand for good quality gasoline in the
country. The focal point for the improvement of gasoline quality, at present is
centered around benzene content of 5% (V/V) with already lead free gasoline
available in India (Ref. Report of Sub-group on the Refining for IXth plan 1996).
It is stated that some of the refiners will be unable to meet the specification of
benzene leading to gasoline production loss. To address the benzene problem in
gasoline it is suggested to increase IBP of reformer feed by adjusting naphtha
splitter cut point which leads to substantial loss in gasoline production volume
and increased quantities of light naphtha. As a result increasing interest is shown
in the development of new catalysts and processes, which allow production of
gasoline with sufficiently high octane numbers, making use of unconventional
low value feed stock such as light naphtha into standard gasoline production. In
addition to this, the demand for LPG is also growing much faster in India at
growth rate of 12 to 13 percent per year. The corresponding deficit of LPG in
2000-01 is 4 million tons and expected to increase up to 7.8 million tons by the
year 2010-2011 (Sundar Rajan Committee Report on Hydrocarbon perspective
1996, Ref LPG News of India, March'96, p 17).
tight naphtha is one of the least viable petroleum feed stocks treated today.
Projected production of straight run light naphtha cut (IBP-130) other than
catalytic reforming feed in India indicates 1-1.25 MMTPA (million metric tons)
of light naphtha is available from various refineries in 1996-97. Light naphtha
mainly contains Cs and C6 hydrocarbons (30 to 40 wt%) depending upon the
source. Due to high percentage of n-paraffins in light naphtha it has lower
research octane number (RON) and high RVP (Reid Vapour Pressure) due to nand
i-pentanes, hence it cannot be used directly for gasoline blending. Thus, the
conversion of light naphtha into other petroleum and petrochemical products
gains significance in this scenario.
Conventionally, gasoline is being produced from the Catalytic reforming process
of naphtha and Fluid catalytic cracking units from various refineries. The
indigenous gasoline production by refineries with low benzene content will be
inadequate to meet the demands in future like at present. The catalyst used for
reforming process is monometallic Pt/Al2O3 or Pt-Re/Al2O3 bimetallic catalyst.
Although these processes are used all over the world, there are number of
limitations in the use of these catalysts. The conventional catalyst is not effective
in promoting aromatization of light naphtha rich in C5 hydrocarbons. The
catalyst is also not very effective in promoting the aromatization of straight
chain paraffins such as n-hexane and n-heptane present in the feed that remain
unconverted. On the other hand, LPG production either from refineries or from
gas fields is not enough to meet the demands. The import situation is also not
encouraging, as only a few private entrepreneurs have actually created facilities
for import market. Therefore the increasing demand for good quality gasoline
and increasing gap between LPG deficit and import capacity also indicates the
need to develop novel processes for the production of gasoline as well as LPG
from cheaply available feed stocks, viz., light naphtha.
There are reports in the literature on the conversion of these straight chain
paraffins into aromatics, using zeolites and metal-doped zeolites as catalyst.
Reference may be made to a process developed by Mobil researchers (Ind. Eng.
Chem. Process. Design Dev., 25 (1986) wherein the preparation of aromatics
from variety of feedstock such as pyrolysis gasoline, unsaturated gases from
catalytic cracker, paraffinic naphtha and LPG have been described.
Another reference may be made to (Patent of Russia Federation No 1141704,
Appl. 17.06.1983) wherein method of producing gasoline fractions from gas
condensate over HZSM-5 catalyst has described. The limitation of this process is
that it utilizes long range naphtha (80-180°C) which is also a feedstock for
catalytic reforming unit.
Another reference may be made to (Hydrocarbon Processing Sept., 1989 p 72)
wherein a process developed jointly by UOP Inc. and British Petroleum, based
on gallium doped zeolite catalyst has been reported. In this process LPG was
converted into BTX aromatics and the process has been demonstrated in a largescale
pilot plant of the British Petroleum Grangemouth refinery in Scotland.
Yet another reference may be made to (US patent 5,026,938 dated 25th June'
1991) wherein a process for converting a gaseous feed stock containing C3-C5
paraffins into aromatics hydrocarbons by contacting the feed with gallosilicate
molecular sieve catalyst has been described.
The draw back of all these processes is that these are mainly related to the
production of aromatics from paraffins of €3 - Cs range which are in high
demand as LPG in India.
Still another reference may be made to US patent 5,125, 415, dated June 1992
wherein the use of Pt-Sn-ZSM 5 catalyst for the production of mono-alkyl
aromatics from Cg n-paraffins containing feed stocks has been described. The
limitation of the above process is production of xylenes from Ca-Cg
hydrocarbons.
Still another reference may be made to (IPA No. 010/DEL/2001 dated
05/01/2001) wherein a process for the conversion of natural gas liquid (NGL)
into liquefied petroleum gas (LPG) and high-octane gasoline over modified
ZSM-5 zeolite has been reported. The limitation of above process is that zeolite
catalyst was modified by steaming method and it produces more LPG (55 wt%)
than aromatics (22wt%).
Still another reference may be made to (IPA No. 2627/DEL/96-dated 29/11/96)
wherein a process for the preparation of a novel modified ZSM-5 zeolite has
been reported. In this process zeolite catalyst was modified by steaming method
followed by acid leaching to remove the extra framework alumina.
The limitations of the above process are firstly formation of high quantity (8-12
wt %) of dry gas (Q+C2) during the n- heptane conversion which will be a loss
to the economy of the process. Secondly the preparation of ZSM-5 catalyst in
this process involves acid leaching step which involves the use of hazardous
mineral acids viz. HC1.
The main object of the present invention is to provide a process for the
production of high-octane gasoline from straight run light naphtha on platinum
containing HZSM-5 molecular sieve catalyst, which obviates the drawbacks as
detailed above.
Another object of the present invention is to provide a process for the conversion
of light naphtha into high octane low benzene content unleaded gasoline as a
blender to boost the octane number along with LPG as by product by using a
catalyst system containing platinum supported ZSM-5 zeolite composite.
Another object of the present invention is to provide a process for the
preparation of platinum metal modified ZSM-5 zeolite catalyst by impregnation
method with out acidity modification by steaming and acid leaching steps.
Yet another object of the invention is to provide a process, which utilizes the straight run light naphtha containing up to 35 hydrocarbon components for the production of high-octane gasoline unlike the other existing processes.
Still another object of invention is to convert C5 -C7 paraffinic and C6- C8 naphthenic components efficiently to produce high-octane gasoline.
Another object of invention is to provide a process that produces in addition to n-paraffinic and naphthenic components, isoparaffins; benzene and other aromatics present in the feed also can be effectively converted to give high octane gasoline with low benzene content and LPG.
Accordingly the present invention provides a process for the production of high-octane gasoline from straight run light naphtha containing C6 to C8 range paraffins and naphthenes on a Pt containing HZSM-5 molecular sieve catalyst which comprises:
(i) impregnating 0.1-2.0 wt% of Pt from tetramine platinum chloride on a HZSM-5
zeolite extrudate, (ii) drying the above said zeolite extrudate at a temperature of 110°C for a period of 10-
12 hrs followed by calcinations at a temperature of 400-600°C for a period of 1-4
hrs in static air, (iii)loading the above said treated Pt impregnated zeolite extrudates in high pressure
reactor and reducing it by passing hydrogen for a period of 2-5 hours at a temperature
of 400-500°C and at a flow rate of 8-12 1/h into the reactor, (iv) cooling the above said Pt impregnated zeolite bed to a temperature of about 300°C
under nitrogen atmosphere and increasing thereafter further bed temperature to 300-
600°C, (v) passing light naphtha through the above said bed at a weight hourly space velocity
ranging from 1 to 8 hrs' and at a pressure in the range of 1 to 25 kg/cm2 and in the
absence of nitrogen to obtain a mixture of high octane gasoline and LPG and
separating the gasoline from the mixture by conventional method..

In an embodiment of the invention the light naphtha feedstock comprises light naphtha containing C6 to C8 range paraffins and naphthenes.
In another embodiment of the invention the reaction temperature is in the range of 400-500°C.
In yet another embodiment of the invention the pressure is in the range of 1-10 kg/cm2.
In another embodiment of the invention the weight hourly space velocity of light naphta is in the range of 2-8hrs-1.
In another embodiment of the invention the Research Octane Number (RON) of straight light naphtha fraction is increased from 64 to 97 in the product with gain of 34 units.
In another embodiment of the invention the platinum impregnated ZSM- 5 zeolite composite used is prepared by incipient wetness method.
In another embodiment of the invention the catalyst used is regenerated by oxidative combustion.
In another embodiment of the invention the total amount of platinum metal added into HZSM-5 molecular sieve is in the range of 0.1 to 1.1 wt%.
In another embodiment of the invention the catalyst used results in the reduction of the sulfur content in light naphtha feed stock from 50 ppm level sulfur to 10 ppm level sulfur in the product.

In still another embodiment of the present invention the process conditions viz.
pressure can be varied to in order to increase the aromatic content and decrease
the LPG in product mixture advantageously.
In the present invention, preparation of the catalyst for the process does not
involve the steps of steaming and acid leaching before the actual catalytic
application. The mentioned catalyst is environmentally friendly as the
preparation does not involve the use of hazardous mineral acids, viz., HC1,
HNO3 etc.
The detailed steps of the process are:
About 18cc of the catalyst (13 g) in extruded form of 1.5 to 2 mm diameter is
loaded in a fixed bed, down flow, high pressure reactor. Before the test runs, the
catalyst is reduced at 450°C with H2 gas for 4 hours with flow rate of 10 1/h. It is
cooled down to 300°C in N2 flow and heated again to desired reaction
temperature. The light naphtha is pumped by plunger type feed pump and N2
flow was stopped totally. Reactor effluents are cooled before being fed to highpressure
separator. The vapors from separator are purged, while the liquid phase
is sent to stabilizer column. Regeneration of the deactivated catalyst in reactor is
carried out by conventional procedure using air and nitrogen mixture. The liquid
product is analyzed using a gas Chromatograph fitted with Tetra Cyano Ethoxy
Propionitrile column and FID detector. The gaseous products are analyzed using
Squalane column.
In the present invention, the process conditions have been optimized for the
controlled d+ C2 (dry gas) yield, which is not desired in the gasoline process. In
order to reduce the duration of regeneration of the catalyst thereby to improve
the catalyst life against the coke lay down, 0.4 wt% of platinum metal is doped
on HZSM-5 catalyst. In the present invention, the novel process developed can
operate for maximization of LPG too by simply altering the process parameters.
The catalyst used in present process is a novel platinum supported HZSM-5
zeolite in which parent ZSM-5 zeolite composite was procured from Zeolyst
international (Lot No. 1822-43). The zeolite to binder ratio of HZSM-5
extrudates were 80:20. These extrudates were impregnated with 0.4 wt% of Pt
from tetraamine platinum chloride (Aldrich) solution. These extrudates were
oven dried at 110°C for 12 hrs and then processed to calcination at 500°C for
3hrs in static air.
The Physico-chemical properties of the zeolite catalyst are as follows:
Characteristics of Parent HZSM-5:
Si-Al ratio (SAR):100; XRD Crystallinity:99%; Catalyst: Pt/HZSM-5; Shape:
Cylindrical form; Diameter: 1.5-2.0mm; Bulk Density: 0.7-0.75 gm/cc; BET
Surface Area: 3 5 0-400 m2/g
The composition of straight run light naphtha used in this process has been
analyzed by GC is shown below.
Light naphtha Feed Composition (wt %):
(Figure Removed)
The following examples are given by way of illustration of the present invention
and therefore should not be construed to limit the scope of the present invention.
EXAMPLE -1
This example describes the characteristics of the high-octane gasoline liquid
product and LPG obtained in the present process from the light naphtha feed
stock. The yields of individual product components that can be obtained in this
process are given. The analysis is based on the GC fitted with Tetra Cyano
Ethoxy Propionitrate column and FID detector.
Table -1
Characteristics of Feed and Liquid Products of this process
Process conditions:
Catalyst: Pt/HZSM-5; Feed: light naphtha of Numaligharh refinery
Reaction Temperature: 450°C; Pressure: 3kg/cm2; WHSV: 6hr"!; TOS: 24 hrs;
Reactor: Micro Reactor of 25 gm-catalyst capacity.
Component Light naphtha Feed (wt%) Liquid
Dry Gas
LPG(C3+C4)
Total Paraffins*
Total Aromatics
Benzene content
Density of the Liquid (g/cc)
Research Octane No. (RON)
Sulphur (ppm)
RVP of liquid (kPa at 38°C)
Existent gum (g/m3)
Potential gum (g/m3)
Distillation
a.Initial Boiling Point(°C)
b.Recovery up to 70°C(%vol)
c.recovery up to 100°C
d.recovery up to 1 80 C
e.Final boiling point(°C)
f.Residue (%vol)
(Figure Removed)
excluding C6-Cg naphthenes of 46wt%
This table shows the conversion of light naphtha feed stock having RON of 64
into aromatics rich (60%) liquid product with low benzene content having a
to
RON 97.4. The novelty of this process is that 85 wt% of high-octane gasoline
was produced from low value feedstock, which could also meet the future
environmental regulations on gasoline in terms of low benzene content and low
sulphur level.
EXAMPLE - 2
This example illustrates the results of effect of temperature on product
distribution of aromatics (BTX) in liquid product, LPG and dry gas. The gaseous
and liquid products were analyzed by same method, which was mentioned in
example 1.
Table - 2
Effect of Temperature on Product Yields
Process conditions:
Catalyst: Pt/HZSM-5; Feed: light naphtha
Pressure: 20 kg/cm2; WHSV: 6 hr'1; TOS: 24 hrs
Temperature ( C)
Ex-reactor yield
(Wt% based on the feed)
(Table Removed)
Table-2 shows that the yield of aromatics (BTX) increases with increase of
temperature and the optimum temperature for the present process was chosen as
450°C due to formation of less coke during reaction.
EXAMPLE - 3
This example includes the results of effect of pressure on the yields and
composition of aromatics and LPG. The product analysis presented in table-3.
Table - 3
Effect of Pressure on Product Yields
Process conditions:
Catalyst: Pt/HZSM-5; Feed: Straight run light naphtha
Temperature: 450°C; WHSV: 6 hr'1; TOS: 24 hrs
Pressure (kg/cm2) 20 3
Ex-Reactor Yields
(Wt % based on the feed)
(Table Removed)
The experimental results reported in table-3 shows that the decrease of pressure
increases the BTX production with decrease in yields of LPG. The optimum
pressure for this process was fixed at 3 Kg/cm2 due to more aromatic formation.
EXAMPLE - 4
This example illustrates the results of effect of weight hourly space velocity on
the yield and composition of high-octane gasoline and LPG. The product
analysis presented in table-4.
Table - 4
Effect of Weight Hourly Space Velocity on Product Yields
Process conditions:
Catalyst: Pt/HZSM-5; Feed: Straight run light naphtha
Temperature: 450° C; Pressure: 3 kg/cm2; TOS: 24 hrs
WHSV (hr"1) o \ 0 2 X f
Ex-Reactor Yields
(W t% based on the feed)
Dry gas 1.0 1.3
LPG
(Table Removed)
From the above table-4, it is shown that the increase of WHSV to 6 decreases the
LPG yield and increases aromatic yields with similar dry gas yields.
EXAMPLE - 5
This example illustrates the effect of run length on the product yield viz. BTX,
LPG and their composition. In the run length of 24 hrs, the product was analyzed
at various intervals and results are presented in table-5.
Table - 5
Catalyst Stability Studies
Process conditions:
Catalyst: Pt/HZSM-5; Feed: Straight run light naphtha; Temperature: 450°C;
WHSV: 6.0 hrs'1; Pressure: 3 Kg/cm2
Time (hrs on - stream) 8 16 24
Ex-Reactor Yields
(Wt% based on the feed)
(Table Removed)
Table-5 shows consistent yield patterns of BTX in Liquid product and decrease
in yields of LPG at WHSV of 6 hrs"1 persists over the run length of 24 hrs.
EXAMPLE - 6
This example explains the effect of catalyst regeneration on the product yields in
the present process of high-octane gasoline production from light naphtha. The
products yield patterns before and after the regeneration was given in the table-6.
Table - 6
Reproducibility of the Ex-reactor yields before and after the Regeneration
Process
Process conditions:
Catalyst: Pt/HZSM-5; Feed: light naphtha; TOS: 24hrs
Reaction Temperature: 400°C; Pressure: 20 kg/cm2; WHSV: 6 hr ~'
Process Performance Before RegenerationAfter Regeneration
Ex-Reactor Yields
(Wt %based on the feed)
Table-6 shows the similar yield patterns of BTX aromatics in liquid product and
LPG in both before and after the regeneration of the catalyst indicating the
complete removal of coke lay down during the reaction.
The main advantages of the present invention are:
l.The process of the present invention converts all types of hydrocarbon
components present in the light naphtha feed viz. Paraffins, isoparaffins,
naphthenes and benzene into aromatic hydrocarbons, isoparaffmic and LPG, at
high selectivity with single catalyst system.
2.Light naphtha, which does not have potential use as conventional reformer
feed stock, can be used as a feed in this process.
3.The catalyst used in this process is ecofriendly and it does not involve the acid
leaching with hazardous mineral acids such as HC1 during preparation.
4.The catalyst used in this process reduces dry gas yields to 2 wt% with increase
of high-octane liquid product and thereby improves the economics of this
process.
5.LPG, which is a by-product in the present process, can meet the industrial and
domestic demands.
6.The process does not require hydrogen during feed cut in.
7.The process also does not require use of corrosive organic chloride additives.
8.The high-octane liquid a major product obtained in the process can be used as
a gasoline blender to boost octane number.
9.This process is economically profitable and depending on the capital
investment the pay back period will be 1.5 to 3 years.
lO.The process maintains constant production of high-octane gasoline pool by
utilization of light naphtha from reformate.
11. The catalyst can desulphurize the synthesized gasoline to lOppm from
SOppm of light naphtha feed.

We claim:
1. A process for the production of high-octane gasoline from straight run light naphtha
containing C6 to C8 range paraffins and naphthenes on a Pt containing HZSM-5
molecular sieve catalyst which comprises
(i) impregnating 0.1-2.0 wt% of Pt from tetramine platinum chloride on a HZSM-5
zeolite extrudate, (ii) drying the above said zeolite extrudate at a temperature of 110°C for a period of
10-12 hrs followed by calcinations at a temperature of 400-600°C for a period of
1-4 hrs in static air, (iii)loading the above said treated Pt impregnated zeolite extrudates in high pressure
reactor and reducing it by passing hydrogen for a period of 2-5 hours at a
temperature of 400-500°C and at a flow rate of 8-12 1/h into the reactor, (iv)cooling the above said Pt impregnated zeolite bed to a temperature of about
300°C under nitrogen atmosphere and increasing thereafter further bed
temperature to 300-600°C, (v) passing light naphtha through the above said bed at a weight hourly space
velocity ranging from 1 to 8 hrs ' and at a pressure in the range of 1 to 25 kg/cm2
and in the absence of nitrogen to obtain a mixture of high octane gasoline and
LPG and separating the gasoline from the mixture by conventional method..
2. A process as claimed in claim 1, wherein the reaction temperature used is preferably in the range of 400-500°C.
3. A process as claimed in claim 1, wherein the reaction pressure used is preferably in the range of 1 -10 kg/cm2.
4. A process as claimed in claim 1, wherein the weight hourly space velocity of light naphta is preferably in the range of 2-8hrs '.
5. A process as claimed in claims 1 to 4, wherein the Research Octane Number (RON) of straight light naphtha fraction is increased from 64 to 97 in the product with gain of 34 units.
6. A process as claimed in claims 1 to5, wherein the platinum impregnated ZSM- 5 zeolite composite used is prepared by incipient wetness method.
7. A process as claimed in claims 1 to 6, wherein the catalyst used is regenerated by oxidative combustion.

8. A process as claimed in claim 1 to 7, wherein the total amount of platinum metal added into HZSM-5 molecular sieve is in the range of 0.1 to 1.1 wt%.
9. A process as claimed in claims 1 to 8, wherein the catalyst used results in the reduction of the sulfur content in light naphtha feed stock from 50 ppm level sulfur to 10 ppm level sulfur in the product.
10. A process as claimed in claims 1 to 9,wherein the pressure is varied in order to increase the aromatic content and decrease the LPG in product mixture.
11. A process for the production of high-octane gasoline from straight run light naphtha on a Pt containing HZSM-5 molecular sieve catalyst substantially as herein described with reference to the examples accompanying this specification.

Documents:

390-DEL-2002-Abstract-(22-10-2008).pdf

390-del-2002-abstract.pdf

390-DEL-2002-CLAIMS-(03-12-2008).pdf

390-DEL-2002-Claims-(06-01-2009).pdf

390-DEL-2002-Claims-(22-10-2008).pdf

390-del-2002-claims.pdf

390-del-2002-complete specification (granted).pdf

390-DEL-2002-Correspondence-Others-(22-10-2008).pdf

390-del-2002-correspondence-others.pdf

390-del-2002-correspondence-po.pdf

390-DEL-2002-Description (Complete)-(22-10-2008).pdf

390-del-2002-description (complete).pdf

390-DEL-2002-Form-3-(22-10-2008).pdf

390-del-2002-forrm-1.pdf

390-del-2002-forrm-18.pdf

390-del-2002-forrm-2.pdf

390-del-2002-forrm-3.pdf

390-DEL-2002-Petition-137-(22-10-2008).pdf

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Patent Number

232571

Indian Patent Application Number

390/DEL/2002

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

18-Mar-2009

Date of Filing

28-Mar-2002

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110 001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	PERUPOGU VIJAYANAND	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
2	SURINDER MOHAN DHIR	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
3	LALJI DIXIT	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.
4	SNEH CHOPRA	INDIAN INSTITUTE OF PETROLEUM, DEHRADUN-248005, INDIA.

PCT International Classification Number

C10G 69/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA