|Title of Invention||
A PROCESS FOR THE PREPARATION OF AN IMPROVED CATALYST FOR LOW-PRESSURE CONTINUOUS ETHYNYLATION REACTION IN PACKED BED REACTORS
|Abstract||The present invention discloses a process for the preparation of an improved more active catalyst suitable for continuous low pressure ethylation reaction in packed beds, which is generated from activated alumina supported catalyst precursor, by the method consisting of : (i) impregnating the said support with a solution of the nitrates of group I and V elements; (ii) decanting the excess quantity of the said solution after impregnation; (iii) roasting the impregnated mass in a forced circulation draft furnace at 300-800 °C; (iv) introducing formaldehyde and acetylene into a packed bed reactor containing the roasted mass at 50-110 °C to generate the catalyst in-situ.|
|Full Text||FORM 2
THE PATENT ACT, 1970
(39 of 1970)
THE PATENT RULES, 2003
(See Section 10, Rule 13)
TITLE OF THE INVENTION
A PROCESS FOR THE PREPARATION OF AN IMPROVED CATALYST FOR LOW-PRESSURE CONTINUOUS ETHYNYLATION REACTION IN PACKED BED REACTORS.
M/s. HINDUSTAN ORGANIC CHEMICALS LIMITED
Mr. A. S. Didolkar, CMD
81, Maharshi Karve Road, MUMBAI -400 002,
PREAMBLE TO THE DESCRIPTION :
The following specification particularly describes the invention and the manner in which it is to be performed.
18 JUL 2008
The ethylation of formaldehyde by acetylene is practiced industrially at high pressure and moderate temperatures. Since acetylene handling at high pressure involves safety hazards, low pressures are being preferred. Use of slurry catalytic reactors for this purpose has limitations of lower process efficiency, safety hazards, and environmental problems due to the presence of copper acetylide. The method of the present invention discloses a low pressure continuous ethynylation process in packed beds, which can eliminate these limitations and achieve a smoother and safer operation by an alternate more active catalyst support.
PRIOR ART :
Ethylation catalysts on various supports, for high as well as low pressure (1-30 kg/cm2) and at moderate temperatures (50 - 140 °C) have been summarized (S. S. Kale et al., Ind. Eng. Chem. Prod. Res. Dev, 20, p. 310, 1981).
Ethynylation reaction at low pressures (less than 2 kg/cm2) and in a temperature range of 50 to 120 °C utilizing fine powder type catalyst with precursors of basic cupric carbonate, CuO, Cu3(P04)2, CuSi04, Cu(OH)2, CuC03 - Cu(OH)2 etc. for ethynylation reaction in slurry reactors are reported [US Patent No. 3,650,985, J. R. Kirchner, Wilmington Dei, E. I. du Pont de Nemours and Co., USA, 1972].
Slurry reactors for ethynylation have also been reported with magnesium silicate supported catalysts [ F. W. Chang et al., Chem. Eng. Sci., 47, p 3793, 1992; US Patent No. 4, 119, 790, E. V. Hort, GAF Corporation, USA, 1978].
Ethynylation catalysts for alkynols production with copper / bismuth precursors on various transitional powdered alumina earners under similar parameters are also described for slurry reactor [US Patent No. 4, 002, 694, E. V. Hort, GAF Corporation, USA, 1977; S. P. Gupte et al., React. Kinet. Catal. Lett., 24, p. 173, 1984; Lin, Xiping, Li, Hongdao, "Shiyou Huagong", 1987, 16, p. 265 (Chinese)].
However, use of powdered catalysts in slurry reactors have their own problems of improper filtration, safety hazards during handling and disposal on industrial scate.
Trickle bed reactors for production of acetylinic diois under similar conditions are also reported for copper and bismuth oxide precursors supported on magnesium silicate and compared to the similar precursors on other supports viz., %" pellets of calcium silicate, 6-12 granular mesh diatomaceous earth and granular silica gel [US Patent No. 2, 871, 273 E. A. Behn, Lake Jackson, Dow chemical Co., USA, 1959].
OBJECTIVE OF THE PRESENT INVENTION :
The present invention discloses a method for the preparation of an active ethynylation catalyst for low pressure continuous packed bed rectors which can operate for longer durations, which can eliminate the present disadvantages associated with the slurry reactors.
DESCRIPTION OF THE INVENTION
The improved catalyst prepared by the method of the present invention can be used for the ethynylation of formaldehyde with acetylene. The catalyst support used for this invention consists of activated alumina, having a particle size range of 2 to 8 mm, preferably 3 to 5 mm diameter and surface are of 200 to 500 m2/g preferably 300 to 350 m2/g. This is comparable to the commercial silica gel support. The steps involved in the preparation of the catalyst precursor from alumina support are as follows :
(i) impregnation of the alumina support with a solution of the nitrates of
group I and V elements; (ii) decantation of the excess quantity of the nitrate solution after
(iii) roasting of the impregnated mass in a forced circulation draft furnace at 300-800 °C.
The Group I and Group V elements are copper and bismuth respectively. The copper and bismuth contents of the catalyst precursor are comparable to those for silica gel supported commercial catalyst precursor, and are in the range of 3 to 12 wt% copper and 1 to 4 wt% bismuth.
The reactants are then introduced into the packed bed containing the catalyst precursor at 50 - 110 °C after initial purging with nitrogen gas and the catalyst gets generated in-situ.
The packed bed ethynylation reactor is operated continuously at a temperature of 50 to 110 °C and a pressure of 1 to 2 kg/cm2. Feed containing 30 wt% formaldehyde of pH 2 to 10, preferably 5 to 8, having methanol content 3 to 4 wt% is used. The outlet formaldehyde concentration (unreacted) varies from 2 to 24 wt%.
The improved catalyst of the present invention, exhibits an activity of 700-1200 g 2-butyne-1,4-diol/lit catalyst/day for longer duration (160-240 hr), for continuous running under the said reaction conditions. The activity in case of the commercial catalyst packed in a similar reactor, is observed to be 200 - 300 g 2-butyne-1,4-diol/lit catalyst/day, under similar process conditions. Thus the catalyst of the present invention exhibits higher activity.
The invention is further described with reference to the following examples which do not limit the scope of the invention.
5000 cc of nitrate solution for impregnation were prepared in the following proportion :
Cu(N03)2 - 3H2O = 1888 g
Bi(N03)3 -5H20 = 227 g
Con. HNO3 = 160 g
Balance demineralized water to bring the total volume to 5000 cc.
800 g of activated alumina support spheres, having surface area 300 to 350 m2/g and particle size, 3 to 5 mm were taken and impregnated with the above nitrate solution. After decantation of the excess nitrate solution, the impregnated alumina was roasted for 8 hours in a forced air draft furnace at 400-450 °C. The impregnated alumina had 3.9 wt% copper and 1.0 wt% bismuth and had a bulk density of 0.96 g/cc.
The said catalyst was packed in a stainless steel reactor equipped with arrangements for continuous feeding reactants and withdrawl of products. Acetylene was introduced after initial purging with nitrogen gas. Aqueous formaldehyde solution (30 wt%) containing 3 wt% methanol of 5 to 8 pH was introduced into the reactor maintained, at 85-90 °C and at 200-500 mm water gauge pressure. The reaction products were continuously collected from the reactor outlet and analysed periodically. Clear liquid was obtained at the reactor outlet and hence the need for filtration was avoided.
Upon continuous running under above reaction conditions for 240 hr, the average catalyst activity achieved was 850 g 2-butyne-1,4-diol/lit catalyst/day.
Example - II
The catalyst for this example was prepared in a similar manner, as described in Example I.
The evaluation of the catalyst was also performed in a similar manner, as described in Example I, except methanol contents in formaldehyde feed. In this run, the methanol content in formaldehyde feed was 0.5 wt%.
Continuous run for 168 hr produced outlet buthynediol solution with average catalyst activity of 400 g 2-butyne-1,4-diol/ltt catalysts/day.
Example - III
This example is given to demonstrate the performance of catalyst prepared on commercially available silica gel support used in commercial ethynylation process. The catalyst for this example was prepared in a similar manner, as described in Example -1, except the catalyst support. For this run, 800 g of commercially available silica gel having surface area 300 to 350 m2/g and particle size, 2 to 3 mm granules were used. The copper and the bismuth contents were 11.0 wt% and 3.2 wt% respectively. The catalyst was packed in a similar reactor as described in Example I, for continuous ethynylation reaction.
Continuous run for 240 hr showed average catalyst activity of 228 g 2-butyne-1,4-diol/lit catalyst/day.
1. A process for the preparation of an improved catalyst suitable for
continuous low pressure ethynyfation reaction, which is generated from
activated alumina supported catalyst precursor, by the method consisting
(i) impregnating the said support with a solution of the nitrates of group I and V elements;
(ii) decanting the excess quantity of the said solution after impregnation;
(iii) roasting the impregnated mass in a forced circulation draft furnace at 300-600 °C and
(iv) introducing formaldehyde and acetylene into a packed bed reactor containing the roasted mass at 50-110 °C to generate the catalyst in-situ for the said reaction.
2. A process as claimed in claim 1, wherein the said reaction is carried out at a low pressure of 1-2 kg/cm2.
3. A process as claimed in claim 1, wherein the activated alumina is used in the form of spheres of 2-8 mm diameter.
4. A process as claimed in claim 1, wherein the activated alumina used has a surface area of 200-500 m2/g.
5. A process as claimed in step (i) of claim 1, wherein the solution of the said nitrates is prepared in dilute nitric acid.
6. A process as claimed in step (i) of claim 1, wherein the said group I element is copper.
7. A process as claimed in step (i) of claim 1, wherein the said group V element is bismuth.
8. A process as claimed in step (i) of claim 1, wherein the impregnation is carried out at 20-35 °C for 20-50 hr.
9. A process as claimed in step (iii) of claim 1, wherein the said impregnated mass is roasted for 2-10 hr.
10.A process as claimed in step (iii) of claim 1 and claim 6, wherein the copper contents in the impregnated mass after roasting is 3-12 wt%.
11.A process as calimed in step (iii) of claim 1 and claim 7, wherein the bismuth content in the impregnated mass after roasting is 1-4 wt%.
12. A process as claimed in step (iv) of claim 1, wherein the concentration of formaldehyde used is 5-30 wt%.
13. A process as claimed in step (iv) of claim 1, wherein the pH of formaldehyde is 2-10.
14. A process as claimed in claims 1 and 12, wherein the methanol content in formaldehyde is 3-8 wt%.
15. A process for the preparation of an improved catalyst of higher activity, as described hereinbefore sufficiently and illustrated in the examples I and III in the specification.
Dated this day of 2008.
For and on behalf of
M/s. Hindustan Organic Chemicals Limited
(ARVIND SRIRAM DIDOLKAR) Chairman & Managing Director
|Indian Patent Application Number||1522/MUM/2008|
|PG Journal Number||09/2012|
|Date of Filing||18-Jul-2008|
|Name of Patentee||HINDUSTAN ORGANIC CHEMICALS LIMITED|
|Applicant Address||RASAYANI, DIST. RAIGAD-410207,|
|PCT International Classification Number||B01J29/70|
|PCT International Application Number||N/A|
|PCT International Filing date|