|Title of Invention
PROCESS FOR THE PREPARATION OF PARA-ETHYL PHENOL
|The present invention relates to a process for the manufacture of an improved gallo-aluminoslicate zeolite catalyst. The process comprises forming an aqueous gel of a compound of aluminium and gallium, an alkali or alkaline earth metal, a compound of silicon and an alkylammonium cation, subjecting such gel to a temperature in the range of 110 to 180°C, and a pressure at least equal to a water vapour pressure, separating crystalline galloaluminosilicate from the mother liquor and washing it thoroughly to obtain said improved catalyst. The present invention also relates to a single step process for the alkylation of phenol to para-alkylphenol using the novel catalyst.
THE PATENTS ACT, 1970 COMPLETE SPECIFICATION
(See section 10; rule 13)
"PROCESS FOR THE PREPARATION OF PARA-ETHYL
We, INDIAN PETROCHEMICALS CORPORATION LIMITED, a Government Company incorporated under the Companies Act, 1956, of P. O. Petrochemicals, District Vadodara -391 346, Gujarat, INDIA.
The following specification particularly describes the nature of the invention and the manner in which it is to be performed:
FIELD OF THE INVENTION
The present invention relates to a single-step process for the manufacture of para-alkylphenol. The present invention also provides a process for the preparation of an improved catalyst for use in the alkylation of phenol to produce para-alkyl phenol. The present invention also relates to catalytic alkylation of phenol to para-alkyl phenol and particularly ethylation of phenol to produce para-ethyl phenol. More particularly the present invention relates to an alkylation process, particularly ethylation process for making para-ethyl phenol, wherein a mixture of phenol and alkylating agent such as ethanol is reacted at atmospheric pressure over a finely tailored zeolite catalyst. The catalyst which exhibits unique shape selectivity effect during ethylation of phenol, comprises of a variable mixture of alumina, silica and pore size regulated crystalline gaUoaluminosilicates. While the invention encompasses alkylation of phenols to produce para-alkyl phenol, for the sake of ease of reference and description, the process will be described with respect to ethylation of phenol to produce para-ethyl phenol. BACKGROUND OF THE INVENTION
Ethylphenol exists in three isomeric forms namely orfho-ethylphenol, para-efhylphenol and meta-efhyl phenol. The para-isomer is industrially important since it is used as intermediates for the production of synthetic resin, antioxidants etc. The conventional process for manufacture of para-ethyl phenol consists of several steps, e.g. (I) sulphonation of ethylbenzene to a mixture of ethylbenzene sulphonic acid mixture, (ii) separation of para-ethylbenzene sulphonic acid, and (iii) alkali fusion of para-ethylbenzene sulphonic acid. Such a process suffers from serious drawbacks like tedious multistep operation, handling of concentrated sulphuric acid and sodium
hydroxide at high temperature which are very dangerous and corrosion of equipment caused by the sulphuric acid. Apart from these, disposal of the wastewater containing sulphuric acid and alkali poses serious environmental hazard. Another shortcoming of the conventional route for para-ethyl phenol, is the large amount of by-products such as ortho-ethyl benzene sulphonic acid and meta-ethyl benzene sulphonic acid, which ultimately lowers the final yield of the desired product.
Catalytic ethylation of phenol to produce ethylphenol mixture is advantageous as compared to the tedious conventional procedures, in terms of safer, simpler and eco-friendliness of operations. Mixture of ortho-ethylphenol, meta-ethylphen and para-ethyl phenol can be conveniently prepared by ethylation of phenol using ethylene or ethanol as alkylating
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agent. A crystalline aluminosilicate zeolite catalyst can be employed. However, in such cases, the ethyl phenol product mixture consists of isomers in thermodynamic equilibrium composition. At about 400°C, the approximate thermodynamic composition of the three isomers are as follows: Ortho-ethylphenol: para-ethylphenol: meta-ethylphenol = 31:17:52 The boiling points of theses isomers are very close to each other and the relative volatility is close to 1. More particularly, the boiling points meta-ethylphenol and para ethylphenol are so close that it is practically impossible to isolate a particular isomer by distillation in a cost-effective manner.
A new type of zeolite catalyst, which is known as ZMS-5, was developed by Mobil Oil Corporation in 1972. The particulars of the method of production of C.ZSM-5 catalyst are disclosed in U.S. Patent No. 3, 702,886.
The details of alkylation of monoalkyl benzene to dialkylbenzenes using ZSM-5 catalyst were revealed in the article published in the Oil and Gas ■ Journal, September 26, 1977 by P.J. Lewis. The pores of this type of catalyst (ZSM-5) have uniform size. As a result, hydrocarbons smaller than the pore dimension are adsorbed and larger hydrocarbons are repelled. Hence, these catalysts are frequently referred to as molecular sieve. There are many precedents of making use of these characteristics to conduct chemical reaction, particularly for petrochemical reactions and petroleum refining processes [Shape Selective Catalysis in Industrial Application, by N.Y. Chen, W.E. Garwood, F.G. Dwyer, 1996, Mercel Dekker Inc., New York]. The ZSM-5 catalyst, characterized by its selectivity, is able to satisfy the needs for high selectivity to products of different molecules. However, the selectivity of ZSM-5, still falls short of expectation in case of isomers of same kind of product. For instance, when phenol is alkylated with ethanol over ZSM-5 catalyst, the selectivity is very high for ethylphenols. However, the ratio of ethylphenols of isomers, e.g. ortho-ethylphenol, para-ethylphenol and meta-ethylphenol are in thermodynamic equilibrium composition.
Various techniques, to enhance the shape selectivity of medium pore aluminosilicates (ZSM-5) have been reported. These modifications enable one to obtain very high product selectivity among dialkylbenzenes, during alkylation of disproportionation of mono-alkylbenzene. In conventional modification method, the zeolite is impregnated with oxides of magnesium, phosphorous and boron, which results in high para-selectivity. However, there are several disadvantages of this modified catalyst. For instance, (i) the
degree of modification is difficult to control, and (ii) the selectivity and activity would change after regeneration.
Catalytic alkylation of phenol with isopropanol or propylene over ZSM-5 type zeolite catalyst to yield a product enriched in para-isomer of propylphenols has been disclosed in U.S. patent 4,391,998. The process was accomplished by contacting phenol and an alkylating agent with the catalyst in the presence of an inert diluent comprising upto about 50 wt% of the reaction mixture. U.S. Patent 4,371,714 describes alkylation of anisole and phenol to 4 methylanisole and 4-methylphenol over ZSM-5 zeolite catalyst duly modified with difficulty reducible oxides such as magnesium, phosphorus, boron, tin, arsenic and antimony. It has also been reported in the said patent that the catalyst requires pretreatment such as steaming, cooking etc, prior to use for alkylation of anisole and phenol. Using a different approach, a process for making a mixture of meta- and para-alkyl phenol over phosphorous or silicon modified zeolite ZSM-5 or silicalite has been disclosed in U.S. Patent No. 4,532,368. The process consists of contacting a mixture of phenol and ortho-alkyl phenol and an alkylating agent e.g. olefins or lower alcohols with a zeolite under alkylating condition to obtain a mixture of ortho-meta-and para-alkyl phenols and separating them at least part of the ortho-alkyl phenol which is recycled to a subsequent alkylation process carried out in the same manner.
However, in all these processes described above, major drawback is the selectivity of the para-isomer in the alkylphenol product mixture. The concentration of the paraethylphenol in the product is always much less than 85%r Thus, scope exists for improvement in the catalyst and the
process for making para-ethylphenol in a single step through ethylation of phenol with an ethylating agent.
The approach for modification of the catalyst can be two fold: (i) tuning down the acidity or the strength of the acid sites by partial or complete isomorphous substitution of the aluminium in the framework of the zeolite, and (ii) passivation of the acid sites located on the external surface of the zeolite as well to finely tailor the pore opening of the zeolite by deposition of bulky organic silicon compounds on the zeolite surface. While wishing not to be limited by theory, it is believed that the acid sites at the external surface are responsible for may undesired non-shaped-selective reactions leading to a lower yield of the desired product. It is also believed that deposition of bulky organic silicon compound on the external surface of the zeolite ultimately generates a very thin layer of silica and thereby blocks the active sites present there. Also the silica layer finely reduces the pore openings of the zeolite, thereby increasing the product selectivity of the catalyst.
Passivation of external surface as well as fine control of pore openings of ZSM-5 zeolite by chemical vapour deposition of tetraethyl orthosilicate, was developed by Niwa and coworkers. The enhancement of para-product selectivity was remarkable in xylenes formed from toluene methylation,
The silicon modified ZSM-5 catalyst, its preparation and use for making high purity para-diethylbenzene from ethylbenzene have been described "by Ikai Wang and co-workers in U.S. Patent No. 4,950,835 (1990), by Bhat et al in Indian Patent No. 178216 (1997) and also Bhat et al In U.S. Patent Ncr. 5,811,613 (1998). In another Indian Patent bearing the number
180 474 (1990), Das et al described process for production of para-xylene and benzene through disproportionation of toluene over such modified zeolite. The potentiality of pore-size controlled zeolite as catalyst to convert a cheap C2-C4 hydrocarbon stream to valuable para-xylene along with benzene and toluene has been disclosed by Bhat et al in the Indian Patent Application No. 56/BOM/96. A further application of pore size regulated zeolite for production para-xylene through methylation of toluene has been described in the Indian Patent Application No. 540/BOM/95. Thus, in recent years, the art of catalyst making has undergone a rapid change and has witnessed the development of catalysts for para-disubstituted aromatics through disproportionation of mono-alkylbenzene, or alkylation of mono-alkylbenzene, aromatization of small and light hydrocarbons. OBJECTS OF THE INVENTION
Accordingly, it is a principle object of the present invention to provide a process for the preparation of an improved catalyst for use in the alkylation phenol to para-alkyl phenol.
It is another object of the present invention to provide a process for the preparation of an improved catalyst having the desired pore size for its use in the alkylation, particularly ethylation of phenol to para-ethyl phenol.
It is yet another object of this invention is to provide a single step process for the alkylation, particularly ethylation of phenol employing a highly selective catalyst, which permits the process to be operated with a very high selectivity for para alkyl phenol, particularly, para-ethylphenol.
It is a further object of the present invention to provide a single step process for the... alkylation , particularly, ethylation of phenol to para-ethyl
phenol wherein use of hazardous chemicals such as concentrated sulphuric acid and alkali at high temperature are avoided.
A further object of the present invention is to provide a process for the alkylation of phenol with an alkylating agent, which operates with alcohol concentration in the range 10-99%, and therefore, hence best suited for a country like India, which has bio-alcohol such as bio-ethanol in abundance.
It is another object of the present invention to provide a process for alkylation of phenol, where the catalyst employed maintains its activity and selectivity for prolonged periods.
Yet another object lies in a process for alkylation of phenol to produce selectively para atkylphenol, wherein the catalyst at the end of prolonged period of use, may be regenerated to obtain the original activity. SUMMARY OF THE INVENTION
The above and the other objects of the present invention are achieved by the process of the present invention which employs an improved catalyst comprising a finely pore size tailored high silica gallo-aluminosilicate zeolite composite in acid form for the alkylation of phenol.
The present invention provides a single step process for the manufacture of para-alkylphenol comprising heating and contacting an initial feed of phenol and an alkylating agent in the presence of a pore size regulated galloaluminosilicate zeolite catalyst comprising a mixture of amorphous silica and pore size tailored crystalline galloaluminosilicate on an alumina support, to form a mixture of alkylphenols containing mainly para-alkyphenols, separating the mixture of alkylphenols from the unreacted phenol and recovering para-alkylphenol with a selectivity of greater than 85%.
Examples of the aluminium and gallium compound employed by the process include corresponding sulphate and nitrate salts. Preferred silicon compounds are sodium silicate, silica sol, while any alkaline or alkaline earth metal salt such as sodium hydroxide, rubidium chloride. N-butyl triethyl ammonium bromide, tetra-propyl ammonium bromide are the preferred alkyl ammonium compounds.
According to a preferred embodiment the dried zeolite (galloaluminosilicate) material is subjected to thermal treatment at a temperature in the range of 450°C to 560°C, preferably at about 538°C, in the presence of a flowing dry air for 8 to 12 hours. Subsequently repeated ion exchange was carried out with the calcined zeolite for four times employing a 12% aqueous ammonium nitrate solution to replace the sodium ions in the zeolite. The material is further converted to active proton form by another thermal treatment at a temperature range of 490 °C to 550 for 8 hours in the presence of dry air to remove ammonia.
In accordance with another feature of the present invention the zeolite material in active form was admixed with suitable binders depending on the specific purpose for which it was employed. Examples of such binders include silica, silica-alumina, alumina sol and hydrated alumina, clays such bentonite and kaolin. The binder mixed composite material was extruded to give cylindrical shape using 1.5 mm die. The extrudates of 2 mm diameter were cut to the length of 10-15 ram. The pellets was subsequently calcined at temperature in the range of 500 °C to 600 °C preferably at 534 °C. The final composition of the extrudates were found to contain 15 to 85% by weight crystalline aluminosilicate (zeolite). The mole ration of silicon to
aluminium in the crystalline material was in the range of 30-50 at the minimum and 120-200 at the maximum.
In accordance to another feature of the invention, catalytic material in the extrudate form was subjected to pore size regulation. The pore size regulation was achieved by contacting the catalyst with a mixture of 8% by volume tetraethyl orthosilicate, 42% by volume methanol and 50% by volume toluene, for varying duration at a temperature in the range from ambient to 300 °C in an atmosphere of nitrogen or air, and calcining at a temperature in the range 510 to 575 °C in presence of air for a required and sufficient duration of time, so as to burn off any residual organic deposit on the catalyst surface.
The extent of pore size regulation was monitored by a standard test reaction in which a reactant mixture consisting of two aromatic compound of different diameter viz. Meta-xylene and ethylbenzene was passed through the catalyst. On the unmodified catalyst (i.e., which is not pore size regulated), the two reactions taking place are: (I) meta-xylene isomerization to ortho-and para-xylene and (ii) ethylbenzene dealkylation to benzene and ethylene. With progressive change in pore opening size during its regulation meta-xylene conversion decreased sharply and reached almost negligible levels, while ethylbenzene dealkylation was not affected to a large extent. The kinetic diameter of meta-xylene is comparable with the zeolite pore diameter and at the same time it is larger than that of ethylbenzene. After the size regulation, the pore size of zeolite is narrowed down and became smaller than the kinetic diameter of meta-xylene. However the size of the narrowed -pore., opening size remained still comparable with those of
ethylbenzene. The point, at which meta-xylene conversion reached a negligible value, indicates the desired pore size regulation.
Experiments and tests were carried out on the catalytic material of this invention established the hydrophobic nature of its chemical structure. These experiments are based on the water and n-hexane that can be sorbed by the pore volume of a given amount of catalyst. It was found that the catalyst was always able to sorb a greater amount of n-hexane than that of water.
The present invention also relates to a single step catalytic alkylation of phenol for the manufacture of para-alkylphenol, with comprises heating and contacting an initial feed of phenol and an alkylating agent in the presence of a pore size regulated galloaluminosilicate zeolite catalyst such as herein described to form a mixture of alkylphenols containing mainly para-alkylphenol, separating in any known manner said mixture of alkylphenols from the unreacted phenol and recovering para-alkylphenol from the separated product with a selectivity greater than 85%. The feed consisting of phenol and alkylating agent is heated to a temperature preferably in the range of 300 to 500 °C and more preferably at 350 to 450 °C. The practical application of this process of phenol alylation referred to herein above can be practiced in number of ways by the skilled practitioner in the art, employing any alkylating agent.. However it has been found convenient to carry out the method employing a cylindrical, down-flow, integral fixed bed reactor in which the catalytic composite material of the present invention is present. Reactant mixture (phenol, alkylating agent etc.) was vaporized and passed through, the catalyst bed at a temperature and flow rates specified
herein after. The reactor effluents were cooled, condensed and collected for analysis by gas chromatograph equipped with flame ionization detector.
The present invention has further improved over the above-mentioned catalyst through the provision of high silica zeolite catalyst comprising a mixture of amorphous silica and crystalline galloaluminosilicates provided on an inert support. The catalyst of the present invention does not contain any Group VIII metals like platinum, palladium, nickel etc.
In alternative form the catalyst can be mixed with water to form an extrudable mass which is then extruded and the extrudates are then dried and calcined, for instance at 813 for 8 hours. By employing the improved catalyst it is possible, according to the present invention to ethylate phenol with ethanol selectively to produce para-ethylphenol.
Accordingly, the present invention relates to a process for the production of para-alkylphenol by the catalytic alkylation of phenol with comprise subjecting a mixture of phenol and an alkylating agent such as herein described to a selected alkylation temperature ranging from 523K -823K in the presence of an improved catalyst comprising of a high silica zeolite composite in acid form to product an alkylphenol mixture containing more than 85% para-isomer and unreacted phenol, separating alkyl phenols in any known manner and recycling the unreacted phenol, back to the reactor.
The alkylating agent may be any alcohol depending upon the final alkylphenol compound desired. Most preferably, the alkylating agent is ethanol and the final product is para-ethylphenol.
Preferably, the high silica zeolite catalyst comprises a mixture of amorphous silica and pores size regulated galloaluminosilicate on an alumina support. The silica to alumina ratio of from 70 to 500 and the silica to gallium ratio from 1000 to 1500 are recommended. The pore size regulation is achieved with a silica precursor compound preferable tetraethyl orthosilicate. Although the reaction can be carried out using nay carrier gas as conventionally employed for conducting petrochemical hydrocarbon reactions, however it has been found that the reaction can be carried out conveniently in the absence of any carrier gas also. The reaction is preferably effected in the absence of any carrier gas.
The reaction can be carried out at a weight hourly space velocity (defined as the weight of reactant passing over the unit mass of catalyst per unit time) from 0.5 to 25 Ir1. The mole ration of phenol to ethanol can be in the range of from 10:1 to 1:4. The aqueous alcohol employed in the reaction can have concentration from 10-99%.
In accordance with a further feature of the invention, the product stream remaining after separation, which is rich in phenol, is recycled to the start of the reaction. The recycled phenol stream may contain from 0.5 to 5% ortho-ethylphenol.
In accordance with a further feature of the invention, the feed (reactant stream) may contain 5-35% water, which is a by-product of the reaction. The presence of water in the phenol ethanol mixture has been found to be beneficial in terms of increased selectivity towards para-ethylphenol, a longer life of the catalyst, and a better yield toward the desired product, Apart form above, the presence steam within the reactor,
helps in removing the excess heat generated through the exothermicity of
the reaction. Thus, the water present in the feed stream serves as a heat sink for the exothermicity of the reaction.
Essentially, the improved catalyst in the process of present invention fulfills the optimum requirement of such a catalyst namely, it is active for selectively ethylating phenol in the para position but inactive for cracking the phenol .moiety and paraethylphenol to other undesired products. Where a selective alkylation process is involved, the activity of the catalyst is expressed in terms of conversion of phenol and selectivity in terms of fraction of para-ethylphenol among ethylphenols formed. These terms are calculated according to the following equations, on alcohol free basis. Phenol Conversion (wt%) = (wt% phenol in feed-wt% phenol in product) x 100
Wt% phenol in feed
Para-ethylphenol selectivity (wt%) = (wt% para-ethvlphenol in product) x 100
Wt% ethylphenol in product The present invention now will be described at length and in greater detail in the following non-limitative examples. In particular the examples underline the fact that, the composition of catalyst, the extent of pore size regulation and the reaction condition under which the invention can be conducted can vary depending on the content of the feed and on the composition desired in the final product mixture. The working examples are presented herein for the purpose of illustration only and must not be construed as limitation of the scope of invention.
PREPARATION OF HIGH SILICA ZEOLITE AND MODICATION BY PORE SIZE REGULATION
A high silica crystalline galloaluminosilicate zeolite was prepared by the following procedure. 1.0187 g aluminum sulphate was dissolved in 26ml water to which 2.97 g concentrated sulphuric acid was added to make solution S1. In a separate beaker another solution S2 was prepared by dissolving 45.697 g sodium silicate in 56.6ml water. A solution of 3.965 g triethyl n-butyl ammonium bromide in 20ml water was added drop b drop with stirring to solution S2. To the resulting mixture of solutions, SI was added drop wise with vigorous stirring. After the addition was completed, the pH of the final mixture was adjusted to 10.5 using dilute sulphuric acid or dilute sodium hydroxide as required. The resulting gel was transferred to a stainless steel autoclave and heated in the range of 110 to 180°C, preferably at 140C for a period in the range of 70 to 150 hours. At the end of this period, the autoclave was cooled in chilled and contents were removed, filtered, washed with hot distilled water and dried at 1I5°C. The solid material was calcined at a temperature in the range of 450 to 560°C, preferably at 538°C in the presence of flowing dry air for 10 hours. It was further ion exchanged four times with 12% ammonium nitrate solution and finally subjected to a thermal treatment at a temperature in the range of 495 to 550°C, preferably at 538°C for 8 hours in the presence of dry air to remove and convert the zeolite to proton form.
The zeolite in the proton form was admixed with inert alumina as binder in the ratio 50:50 by weight and mixed thoroughly to form a homogeneous mass. It was then extruded to 1.5mm diameter cylindrical pellets and sized to 10-15 mm length. The pellets were subsequently calcined at a temperature in the range 500 - 600°C, preferably at 543°C. / The catalytic material in the extrudate from was subjected to pore size regulation. The pore size regulation was achieved by chemical vapour deposition of silica employing tetra-ethyl orthosilicate as silica precursor. 5g of extrudate form of catalyst was kept in a fixed bed down flow reactor. The catalyst bed maintained at a temperature in the range of 180 - 250°C, was contacted with a mixture consisting of 8% by volume tetraethyl orthosilicate, 42% by volume methanol and 50% by volume toluene for varying duration with nitrogen as a carrier gas. The material was then calcined at a temperature in the range of 510-575°C, preferably at 542°C in the presence of dry air for a period of time in range of 2 - 20 hours. The extent of pore size regulation was monitored by a standard test reaction It involves passing a mixture of 75% meta-xylene and 25% ethylbenzene through the catalyst bed maintained at 408°C using hydrogen as a carrier gas. The duration of silica deposition reaction, after which the zeolite shows nearly zero meta-xylene conversion, the reaction, was stopped. At this stage the zeolite has got the right pore size with most of its non-selective active site at the external surface covered by silica so as to prevent undesired reactions. EXAMPLE 2
This example shows the comparison of catalytic performance of the parent galto-aluminosilicate zeolite and the pore size regulated zeolite for the
ethylation of phenol of phenol and the selectivity towards the para-ethylphenol as the desired product. The comparison has been made at about similar conversion level of phenol, in order to nullify any effect on the selectivity for para-ethyl phenol because of the difference in conversion level. Such a situation was achieved by carrying out experiments and generating data at different the weight hourly space velocity for both the catalysts, while other experimental conditions were kept same.
PEROFRMANCE COMPARISON OF PARENT AND PORE SIZE REGULATED GALLO ALUMINOSILICATE ZEOLITE FOR PHENOL ETHYLATION
Si02/A1203 ratio = 75, Temp = 400C, PhOH:EtOH (mole) = 2:1
Parent zeolite Pore size tailored zeolite
Lighters and other aromatics 2.74
o-Ethyl phenol 1.76
p-ethyl phenol 1.43
m-Ethyl phenol 0.66
Phenol conv,, wt% 7.56
Ethylphenol yield wt% 53.7
Para-EtPhOH Selectivity, % 37.1
This example illustrates the relationship between the amount of silica deposition on the zeolite and the enhancement of para-isomer content in the
reactor effluent. The amount of silica deposition actually represents the
extent of pore size regulation as discussed herein before.
SILICA DEPOSITION AND PARA-SELECTIVITY ENHANCEMENT OF GALLO-ALUMINOSLICATE ZEOLITE DURING PHENOL ETHYLATION
Si02/A1203 ratio = 75, Temp: 400C, WHSV - 12h-l, PhOH: EtOH (mole) = 2:1
Silica deposition wt% 0 . 3.75 70.0
Phenol Conv, wt% 35.55 15.18 5.3
Ethylphenol yield wr% 75.1 73.3 83.4
Para-EtPhOH Selectivity, % 18.7 46.36 88.2
It can be seen that with increase in silica deposition on the gallo-aluminosilicate zeolite, the concentration of for para-ethylphenol in the ethylphenol product mixture increases. EXAMPLE 4
This example shows the effect of addition of water to the reactant stream on the performance of catalyst. Two sets of experiments were carried keeping all other conditions identical except the water component. In set 1, experimental run was carried out without adding water to the feed stream, and, in set II 20 wt% water (based on phenol) was added to the feed stream.
EFFECT OF ADDITION OF WATER TO THE REACTANTANT STREAT ON
THE CATALYST PERFORMANCE
Phenol Conv., wt% Ethylphenol yield, wt% Para-EtPhOH Selectivity %
Experiment Set I Set II
Addition of water to the reactant feed stream improves the phenol conversion, ethylphenol yield and the selectivity, of/the para-ethylphenol. It may be pointed out here that water is a product of the reaction of phenol ethylation. Also, because of high heat capacity, water can serve as a heat sink within the reactor, to absorb the heat generated through the exothermicity of the reaction. EXAMPLE 5
This example illustrates the influence of reaction temperature on the pore-size tailored zeolite catalyst performance for the ethylation of phenol to para-ethylphenol.
EFFECT OF REACTION TEMEPERATURE ON THE CATALYST PERFORMANCE
WHSV = 12h-l, PhOH: EtOH (mole) = 1:1
Temperature 375 500 425
Phenol Conv, wt% " 5.69 8.09 9.05
Para-EtPhOH Selectivity, % 88.1 86.2 85.1
The results given above indicate that the reaction temperature plays an important role in deciding the extent of phenol conversion the para-ethylphenol concentration in the ethylphenol product mixture. There is an increase in the phenol conversion and ethylphenol yield with enhancement of reaction temperature, however the selectivity for para-ethylphenol decreased slightly. EXAMPLE 6
This example illustrates the influence of contact time of the reactants with the catalyst (expressed in terms of weight hourly space velocity) on the
performance of pore size tailored zeolite for ethylation of phenol to para-
EFFECT OF WHSV ON THE CATALYST PERFORMANCE Si02/Al203 ratio = 75, Temp - 400C, PhOH:EtOH (mole) = 1:1
WHSV, h-1 3 6 9 20
Phenol Conv, wt?/o 13.9 10.87 8.09 7.03
Para-EtPhOH Selectivity, % 80 84.4 86.2 90
With increase in WHSV, the phenol conversion as well as yield of ethylphenols decreases, but the selectivity for para-ethylphenol enhanced.
This example illustrates the effect of composition of the reactant
mixture on the performance of pore size tailored zeolite. The composition of
the reactant mixture is expressed in terms of phenol to ethanol mole ratio.
Performance of the catalyst is expressed in terms of phenol conversion,
ethanol yield and para-ethylphenol selectivity.
EFFECT OF WHSV ON THE CATALYST PERFORMANCE Si02/A1203 ratio - 75, Temp - 400C, PhOH: EtOH (mole) = 1:1
Phenol: Ethanol (mole) 05 1.0 2.0
Phenol Conv., wt% 12 10.66 5.3
Para-EtPhOH Selectivity, % 86.5 87.34 88.2
With increase in phenol to ethanol more ratio, the phenol conversion as well as- yield of ethylphenols decreased, but the selectivity for para-ethylphenol remains almost constant.
This example exemplifies the catalyst life and stability, i.e. the ability
of the catalyst to maintain its activity and selectivity for prolonged periods
for ethylation of phenol selectivity to para-ethylphenol.
LIFE AND STABILITY OF THE PORE SIZE TAILORED GALLO-ALLUMONSILICATE ZEOLITE CATALYST FOR PHENOL ETHYLATION
Temp = 400C, WHSV - 12h-l, PhOH: EtOH (mole) = 1:1
Time on stream, hour 2 5 10 20
Phenol conv, wt% 8.33 8.7 8.6 8.7
Para-EtPhOH selectivity, % 86 86 86.1 86.6
The above results show that the catalyst can serve for a prolonged duration of time on stream for ethylation of phenol. EXAMPLE 9
This example shows the regenerability of the catalyst. The catalyst was coked intentionally and then regenerated by burning off the coke at 540C in a continuous flow of moisture free air. Coking and regeneration were done repeatedly to examine and ensure the repeated regeneration of the catalyst. The regenerated catalysts were tested for phenol ethylation.
REGENERABILITY OF THE PORE SIZE TAILORED GALLOALUMONOSILICATE ZEOLITE CATALYST FOR PHENOL ETHYLATION
Temp. = 400 °C, WHSV = 12h-*, PhOH:EtOH (mole) =1:1
Number of regeneration I 1 3
Phenol Conv., Wt% 8.4 8.6 8.5
Para-EtPhOH Selectivity % 86.4 86.2 86.3
The above result show that the catalyst can be regenerated several times.
1. A single step process for the manufacture of para-alkylphenol, which comprises heating and contacting an initial feed of phenol and an akylating agent such as herein described, characterized in that said process is carried out in the presence of a pore size regulated galloalummosilicate zeolite catalyst comprising a mixture of amorphous silica and pore size tailored crystalline galloaluminosilicate on an alumina support, to form a mixture of alkylphenols containing mainly para-alkylphenol, separating in any known manner said mixture of alkylphenols from the unreacted phenol and recovering para alkylphenols from the unreacted phenol and recovering para alkylphenol from the separated product with a selectivity greater than 85%.
2. A process as claimed in claim 1 wherein said initial feed consisting of phenol and alkylating agent is heated to a temperature preferably in the range of 300 to 500°C.
3. A process as claimed in claim 2 wherein said temperature is in the range of 350 to 450°C
4. A process as claimed in any one of claims 1 to 3 wherein said alkylating agent is an alcohol.
5. A process as claimed in claim 4 wherein said alcohol is ethanol.
6. A process as claimed in claim 1 wherein the silica to alumina ratio in said catalyst is from 30 to 500 and the silica to gallium oxide ratio is in the range of 1000 to 1500.
7. A process as claimed in claim 1 or 6 wherein the pore size of the catalyst is regulated using a tetraethyl orthosilicate as a silica precursor.
8. A process as claimed in one of the claims 1 to 7 wherein said reaction is carried out in the presence of water as a co-feed.
9. A process as claimed in any one of the claims 1 to 8 wherein the reaction is effected at weight hourly space velocity of 0.1 to 40 per hour.
10. A process as claimed in any of the claims 1 to 9 wherein the composition of the feed mixture of phenol to said alkylating agent in terms of mole ratio is 1:5 to 5:1.
11. A process as claimed in claim 10 wherein said alkylating agent is aqueous ethanol in a concentration of 10 to 99%.
12. A single step process for the manufacture of para-alkylphenol substantially as herein described with reference to as illustrated in the foregoing examples 2 to 9.
Dated this the 11th day of August 2004.
(H. SUBRAMANIAM) Of Subramaniam, Nataraj & Associates Attorneys for the Applicants
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|INDIAN PETROCHEMICALS CORPORATION LIMITED
|P.O. PETROCHEMICALS, DISTRICT VADODARA - 391 346,
|PCT International Classification Number
|PCT International Application Number
|PCT International Filing date