Title of Invention

"AN IMPROVED CATALYST AND TO A PROCESS FOR THE PREPARATION THEREOF"

Abstract This invention relates to a process for preparing an improved catalyst suitable for producing methane rich gases. According to the process an aqueous solution of metal nitrates is reacted with aqueous alkali solution containing silica and alumina to form mixed precipitated slurry. The said precipitate and calcining is washed and dried with said precipitate.
Full Text FIELD OF INVENTION
This invention reflates to a process for preparing an improved catalyst for producing methane r i ch gases. PRIOR ART
Production of methane containing gasses such as town gas by reacting steam and C^HCjra hydrocarbons is practiced since more than 5® years. Pre—re-forming technology has gained universal acceptance as a means of solving problems associated with tubular steam reforming at elevated temperatures . Severe coking of the catalyst necessitates -frequent shut down in commercially operating plants. Therefore, in recent years, an adiabatic pre—reforming system is introduced to safeguard the tubular re-forming process and to decrease the carbon formation in primary reforming catalysts. Pre—reforming catalysts are operating at lower temperatures (400—5fiH8°C) and low steam to carbon ratio. Since most of the catalyst poisons are removed in the pre-reformer bed, overall efficiency of downstream process is improved. Further, it results in good improvement in process economy.
A survey of patent, literature indicates that a combination of nickel oxide and various promoters on different supports are extensively investigated for low temperature steam-naphtha reforming, A lanthanide rare earth promoter was used in U.S. Patent No.3404100 in a coprecipitated Ni/catalyst -for reforming in the temperature range 320-480°C. Methane rich gas process using a combination of NiO, CuO, CroOT, MnO and SiO^> for
operations at temperatures as low as 300—325°C has been

Process has been described in German Offen. 230628 using potash promoted Mi/Al .^Uj catalyst operating at
430—450°C arid steam to carbon ratio 1.6. Lanthana orceria promoted Ni/A^Ghj catalyst was prepared for the synthesis of methane containing gases by the decomposition of steam and ^2~^i2 hydrocarbon in the temperature in the range 300—550°C and as described in German Offen, 2739466.
Steam-reforming is often accompanied by carbon forming reactions and therefore Ni catalyst has to be supported on suitable materials so as to achieve an equilibrium between carbon formation and carbon removal under opearing conditions. It is very difficult to achieve this condition since Ni catalyst is sensitto changes in feed composition. Hence the choice o-f a suitable support which could resist, carbon -formation is usually preferred. OBJECTS QE THE INVENTION
An object o-f this invention is to propose an improved catalyst, for producing methane rich gases and a process for the preparation, said catalyst having ar« advantageous application for producing methane rich gases.
Another object of this invention i» to propose an improved catalyst for producing methane rich gases and a process for the preparation, said catalyst having a high activity, selectivity and stability even at high naphtha space velocity, low temperature and low steam to hydrocarbon ratio.
Still another object of this invention is to propose an improved catalyst for producing methane rich gases and a process for the preparation, said catalyst having high nickel dispersion.
Vet another object of this invention is to propose an improved catalyst for producing methane rich gases and a process for" the preparation, said catalyst having high reducibility properties.
A further object of this invention is to propose an improved catalyst for producing methane rich gases and a process for the preparation, said catalyst having high coke resistance properties.
Further objects and advantages of this invention will be more apparent from the ensuing description.
BRIEF DESCRIPTION OF THE INVENTION
According to this invention there is provided a process for preparing improved catalyst for producing methane rich gases comprising of:-
a) reacting an aqueous solution of metal nitrates selected from nickel
magnesium and lanthanides with aqueous alkali containing silica and
alumina maintaining pH range of 7.0 to 10.0 and at a temperature
range varying from ambient to 85°C, to form mixed precipitate slurry,
b) precipitated slurry washed from DM water to remove impurities
sodium and sulphur,
c) drying the precipitated slurry,
d) calcining the precipitate at 350°-550°C to control metal support
interaction,
filtered and the cake is dried in band/ box dryer at 350-550°C to control the loss on ignition between 3-10%. The oxide is mixmulled with DM water and graphite (1 to 3%) and dried at 100-200°C to control loss on ignition between 4-13%. It is further granulated over 12-100 sieve and tabletted in the size 3mm x 3mm or 4.7mm dia. x ht. Finally it is calcined at 350°C-550°C.
The catalysts thus prepared have the composition in the range as given below:
% by wt.
NiO 50-75
MgO 5-12
A1203 7-15
SiO2 2-23
Lanthanide oxides 4-18
The catalyst prepared by the process of this invention has a surface area of 160-250 m2/g, a total pore volume of 0.18 to 0.30 m!3/g and mesopores of between 20 to 40% of the total pore volume, a bulk density of 0.8 to 1.2 g/ml.
The following metal salt solutions are used for the preparation of 1 kg. of all the catalysts.
Solution I 2500g of Ni (NO3)2. 6H2O in 10L of DI water Solution II 200g Ce(NO3)3. 6H2O in 1L DI water Solution III 200g La(NO3)3. 6H2O in 1 DI water Solution IV 300g Mg (NO3)2. 6H2O in 1 DI water
Solution V 22 The following supports were also used -for the
preparation o-f catalyst samples.
1. Silica containing 80X SiO2 and rest
2. Activated alumina containing 7(3% AQ? (micronised to particle size & rest
3. Activated magnesia containing 85% HgO and rest
H2O/CO2
EXAMPLE A
A mixture o-f solutions I, 11 and III was slurried into 5 This catalyst preparation is very similar to Example A, except that the supports used (silica,
magnesia and alumina) were hydrothermally treated before being taken for precipitation. Hydro thermal treatment of the support were carried out in a steam autoclave at 200-220°C for 16 h. This method yields a catalyst which could impart extra stability for the support. Support provides a very vital role in providing the reaction sites to the chemisorption of steam during naphtha reforming.
EXAMPLE C
Catalyst prepared by methods A 85 B were analysed several times
and the composition is as follows:
NiO/AI2O3/MgO/SiO2/La2O3/CeO2 65/ 10/5/4/B/B
Method of preparation of reference catalyst R
Reference catalyst R was prepared following the technique described in U.S. Patent No. 3404100). 1500g Ni (NO3)2 6H2O and 1480g AI (NOsJs- 6H2O was dissolved in 6 L DI water, stirred and the solution was brought to 50°C. Then, 2080g NH4HCO3 were added with stirring maintaining the slurry at 50°C. The slurry was filtered and washed. To the resultant precipitate was added 123g each of lanthanum nitrate and 61.5g cerium nitrate dissolved in little deionised water. The catalyst thus prepared was dried overnight at 110°C and calcined for 4 hr at 400°C.
Evaluation results No. 1
The catalyst of methods A 85 B and the reference catalyst R were evaluated for naphtha steam reforming activity in a high pressure flow reactor after reducing 50cc of the catalyst with hydrogen at 400°C for 18 hr at a space velocity of 2000h"1 and at atmospheric pressure and further reduction at 18 atm for 2 hr. Reaction was carried out with steam to naphtha weight ratio of 2: 5 at 380-420°C and 18 kg/cm2 pressure. The product gas contains 0.1-0.6% CO, 20-24% CO2, 58-64% methane and balance hydrogen. No naphtha slip was observed while testing for 50 hrs. for all the catalysts.
Evaluation Result No. 2
All the catalysts were evaluated as per the test conditions in evaluation No.l except that steam to naphtha wt. Ratio was reduced to 1.5. Testing at this low S/C ratio indicated the extent of carbon deposition in the following order. R> A and B though and no naphtha slip was observed.
Evaluation Result No. 3
For calatysts A and B silica was estimated in the condensate collected after testing as per evaluation in 1 & 2. % silica migrated in both cases were found to
be in the range 0.002 to 0.0025 which indicates that silica migration is negligible for the catalysts of pr esent i nven t i on. Evaj.uatj.Pn Resuit No.4
The test conditions were maintained identical to evaluation no.2 except that t.he operating temperature was lowered to 340°C when trace* o-f naphtha was observed in the condensate for all the catalysts upto 340°C no naphtha slip was observed. Evaluation Result Naftj5
The test conditions were maintained similar to evaluation no.i except that the aromatic content in the •feed stock was varied -from 10-607.. No naphtha slip was observed upto 40% aromatics in the feed while testing for 20hrs. duration. However at 60X aromatics in the
feed naphtha slip observed was in the range 6 to 85C and the following trend was observed. R > A and B
Evaluation Result No.fr
Effect of higher feed rates of hydrocarbon was particularly studied for catalysts A and B in comparison to the reference catalyst R. The catalysts were tested at a high naphtha space velocity of 8.0, operating temperature 450°C and pressure maintained at
2 I0kg/cm . Lined out naphtha slip after 8 hours run for
catalysts A, B and K are 33% t 36% and 37%. Hence activity for these catalysts at higher space velocities shows the following trends
A and B > R Evaluation Result No.7
Physical integrity of the catalysts were evaluated by subjecting the catalysts to various high temperature/hydrotherroal treatments. The catalysts were heated 500°C and plunged in cold water. Maximum retained crush strength (S3%) was observed for catalyst A. Further, crush strength was determined after refluxing the catalysts in water for 2h. In both the cases, the 7. retained crush strength was in the order A and B > R. The discharged catalysts, after activity evaluation also show the same trend in percentage retained crush strength. Percentage surface area loss on subjecting the catalysts to thermalXhydrothermal treatments or after test run was also found to be minimum for catalyst ft (24—35%). Evaluation Result No.Q
Acidity determinations were carried out by NHkj—TPD. Acidity of catalysts A and B are comparable and lower than that of the reference catalyst R,
Further, compared to catalyst R, the ammonia desorption
is higher at lower temperatures for catalysts A and B.
Strength of acid sites responsible for carbon
deposition are lower for A and B compared to catalyst
R.
Evaluation Result No,9
The nickel dispersi on as well as 7, nickel reducibility Mere evaluated and are found to be maximum for catalyst C. The dispersion follows the trend A and B > R and '/, reducibility follows the orders A and B



WE CLAIM:
1. A process for preparing improved catalyst for producing methane rich
gases comprising of:- reacting an aqueous solution of metal nitrates selected from nickel
magnesium and lanthanides with aqueous alkali containing silica and
alumina maintaining pH range of 7.0 to 10.0 and at a temperature
range varying from ambient to 85°C, to form mixed precipitate slurry,
a) precipitated slurry washed from DM water to remove impurities
sodium and sulphur,
b) drying the precipitated slurry,
d) calcining the precipitate at 350°-550°C to control metal support
interaction,
e) catalyst obtained by step d) has a surface area of 160-250 m2/g, total
pore volume of 0.18 to 0.30 ml3/g and mesopores of 20 to 40% of the
total pore volume, bulk density of 0.8 to 1.2 g/ml.
2. The process as claimed in claim 1 wherein nitrates of nickel,
mangesium and lanthanides are precipitated over silica and alumina.
3. The process as claimed in claim 1 wherein nitrates of nickel and
lanthanides are precipitated over magnesia, silica and alumina.
4. The process as claimed in claim 1 wherein a combination of silica,
magnesia and alumina are used as support material for the catalyst
preparation.
5. The process as claimed in claim 1 wherein oxides of lanthanide in the
range 4-18% are used as promoters.
6. The process as claimed in claim 1 wherein the precipitation is carried
out by addition of acidic components to alkali or base components.
7. The process as claimed in claim 1 wherein mixed precipitate of
magnesia, silica and alumina was autoclaved and used as a support.
8. The process as claimed in claim 1 wherein the said precipitate is allowed to age in precipitation vessel for 1 to lOhr at temperature ranging from ambient to 90°C to control the pore volume and NiO crystallite size.
9. The process as claimed in claim 1 wherein magnesia is used as a part of the support to minimise the acidity of the catalyst and thereby to improve the coke resistance property.
10. The process as claimed in claim 1 wherein aluminium silicate
formation is prevented by identifying suitable formulations for the
preparation of the catalysts.
11. The process for preparing improved catalyst suitable for producing
methane rich gases substantially as herein described and
illustrated.

Documents:

675-del-1998-abstract.pdf

675-del-1998-assignment.pdf

675-del-1998-claims.pdf

675-del-1998-complete specification (granted).pdf

675-del-1998-correspondence-others.pdf

675-del-1998-correspondence-po.pdf

675-del-1998-description (complete).pdf

675-del-1998-form-1.pdf

675-del-1998-form-19.pdf

675-del-1998-form-2.pdf

675-del-1998-form-3.pdf

675-del-1998-form-5.pdf

675-del-1998-form-6.pdf

675-del-1998-pa.pdf


Patent Number 243657
Indian Patent Application Number 675/DEL/1998
PG Journal Number 45/2010
Publication Date 05-Nov-2010
Grant Date 28-Oct-2010
Date of Filing 18-Mar-1998
Name of Patentee A. A. LALLJEE
Applicant Address 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA
Inventors:
# Inventor's Name Inventor's Address
1 B. SEN 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA.
2 K.K. ABDUL RASHEED 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA.
3 S.M. MOULANA 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA.
4 V.S.M. THAMPURAN 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA.
5 R.P. MALHOTRA 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA.
6 K.T. JOSE 402/403, MANSAROVAR, 90, NEHRU PLACE, NEW DELHI-110 019, INIDA.
PCT International Classification Number C01G 53/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA