SU721116A1 - Method of preparing borophosphate catalyst for producing isoprene - Google Patents

Description

one

This invention relates to methods for preparing catalysts for the production of isoprene, in particular to a method for preparing a borophosphate catalyst used to convert 2-methylbutanal to isoprene. A known method for the preparation of borophosphate catalyst for 1–10 wt.% Phosphoric acid, which involves evaporation of a mixture of concentrated phosphoric acid and finely divided boric acid, drying, grinding, and calcining the resulting EU borophosphate. The known method does not provide a catalyst with high, catalytic properties in the production of isoprene by decomposition of 2-methylbutanal.

; The closest solution to the set-up is to prepare a borophosphate catalyst, including; evaporation of a mixture of equimolar amounts of concentrated phosphoric and finely divided boric acids, drying of the obtained boron phosphate, grinding it and calcining at 300-1200С 2. However, this method does not provide a catalyst with the specified

chemical composition. The reason for the non-reproducibility of the composition of the catalyst is the uncontrolled volatilization of phosphoric acid to Slide when the mixture of phosphoric and boric acids is evaporated and the formation of polymer chains РГ-О-Р instead of b-О-Р in the process; high temperature processing which results in the formation of

0 borophosphate catalyst with admixture of free boric anhydride. The catalyst obtained in a known manner, does not have high enough activity with selectivity:

5 at 350 ° C, the selectivity of isoprene formation is 61.1-88.4 mol.%, With a conversion of 2-methylbutanal 64.892, 1 mol.%.

The aim of the invention is to obtain a catalyst with increased activity and selectivity.

The goal is achieved by the described method. Preparation of a borophosphate catalyst, including mixing equimolar amounts of concentrated boron and finely ground; phosphoric acid, evaporation of the mixture, grinding and calcining, and the additional treatment of the calcined catalyst with a vapor-air mixture containing 15–75% by volume of a molten carbonate containing 15–75% by volume. 450-650 ° C for 1-8 hours. Further treatment of the catalyst with an air-steam mixture containing 15-75% by volume of water vapor and carried out at 450-650 ° C for 1-8 hours allows complete remove unbound boric anhydride as boric acid. The catalyst obtained by the process described allows for a process with selectivity to 64 isoprene (5-92.5 mol.% For 2-methylbutanol conversion of 90.1-94.6% by volume. Example 1. A borophosphate catalyst was prepared with Atomic ratio B: P - 1.00 is mixed with 121.4 mi of an aqueous solution of orthophosphoric acid (d If725) and 117 g of finely divided boric acid and then the mixture is evaporated in a water bath. The dry catalyst is crushed and calcined for 1 h. in a stream of air with a gradual treatment of the catalyst with an air-steam mixture containing 50% by volume of steam at within 1 hour, the ratio of B: P-1.01, the conversion of 2-methylbutanal to isoprene is carried out in a quartz isothermal flow-type reactor.After heating the reactor to 35 ° C, into the reactor 2-methylbutanol is fed at a rate of 6.0 hours in liquid. Conversion of 2-methylbutanal is 94.0% by volume, the selectivity of isoprene formation is 92.5 mol%. P RIM ep 2. Borophosphate catalyst is prepared as in Example 1 with the difference that the calcination is carried out for 1.5 hours in a stream of air and for 3 of its processing so as to vapor-air mixture Sue containing 20 vol.% steam, at 500 ° C. The atomic ratio B: P in the catalyst is 1.00. The 2-methylbutanal conversion process is carried out as in Example 1. The conversion is 94.6% by volume, the selectivity is 87.4% by mol. Example 3. Vorophosphatic catalysis was prepared as in example 1, with the difference that it was caked at 650 s for 3 hours in the air current and then steam-air mixture containing 15 vol.% Of steam at the current for 4 hours. The atomic ratio B: P in the catalyst is 1.02. The 2-methylbutane conversion is 90.1% by volume and the conversion to isoprene is 85.1 mol%. Example 4. A borophosphate catalyst is prepared as in Example 1 with the difference that it is calcined for 5 hours in a stream of air and for .8 hours at 450 ° C. The vapor-air mixture containing 75 vol.% steam is worked. The finished catalyst has an atomic ratio B: P of 1.01. The 2-methylbutanal conversion is 92.4% by volume, the selectivity to isoprene is 89.5%. Example 5. To prepare a borophosphate catcher with an atomic ratio B: P - 1.00, 122.4 mm of an aqueous solution of orthophosphoric acid (1.654J and 124 g of finely divided boric acid) are mixed. After evaporation of the mixture, the dry catalyst is crushed and calcined at 10 hours in air flow, then for 6 hours at 550 ° C, the catalyst is treated with a vapor-air mixture containing 20% v / v. The finished catalyst has an atomic ratio B: P - 1.01. Conversion to 2-methyl-butanal is 20.8% .% Isoprene formation of 92.3 mol.%. Example 6 (for four) Borophosphate catalyst samples with an atomic ratio B: P - 1.00 are prepared, removing in each case 121.4 ml of an aqueous solution of orthophosphoric acid (dj 1.725) and 117 g of finely divided boric acid. The mixture is evaporated on a water bath, the dry catalyst is calcined with BOOS for 1 i in an air stream. The finished catalysts are analyzed for the boron: phosphorus ratio and used in the conversion process 2-methylbutanal to isoprene. The process is carried out in a quartr isothermal flow type reactor. The catalyst is heated to the reaction temperature and 2-methylbutanal is fed at a rate of 6.0 hours by liquid through an evaporator at 350 ° C and atmospheric pressure. The atomic ratios of boron and phosphorus in the catalysts obtained and their catalytic properties are given in the B table.

 92.1

88.4 68.3 65.7 4.8 70.2 71.0 61.1

Thus, the proposed solution provides a catalyst with a given atomic ratio of B: P and improved catalytic properties in the decomposition reaction of 2-methylbutanal to isoprene, in addition, it is possible to reuse unreacted boric acid and reduce the consumption of concentrated phosphoric acid.

Claims (2)

1. The patent of France 2,164,826, cl. From 07 From 1/00, published. 1973. 2. Clean up G.P. et al. Catalys of congestion of the main organic synthesis, L, 1974, 145 (prototype).