Isopropanol synthesis from propylene

Abstract

Isopropanol was catalytically synthesized form C3H6 and H2O in a through-flow tubular reactor. The constructed reactor set was made of polished stainless steel to prevent corrosion from H2O and was designed to withstand a pressure of 100 atg at a maximum temperature of 400C. The zeolite catalyst was NaY composed of SiO2/Al2O3/Na2O = 66.7 : 20.3 : 12.3. The NaY catalyst was ion-exchanged to H-Y form for use in the synthesis. It was found that selectivity for isopropanol generally increased with space velocity from 2,000 hr-1 to 8,000 hr-1 and with temperature from 200C to 230C. Above 230C the selectivity for isopropanol tended to decrease. With respect to space time yield (STY) it was found that maximum isopropanol STY of 2.33 mol/l-cat.hr occurred at 8,000 hr-1 when the pressure was 75 psig. The STY generally increased as temperature increased from 200C to 250C. It begin to decrease when temperature exceeded 250C. With respect to product distribution it was found that at a temperature higher than 250C, with space velocity 2,000 hr-1 and pressure 105 psig, side reactions would predominate. Overall, the optimum space time yield of isopropanol was observed to be 2.33 mol/l-cat.hr at 230C, 75 psig and space velocity 8,000 hr-1 . Comparison of the present experimental results with those obtained by Wiwut Tanthapanichakoon using an ion-exchanged Na-mordenite catalyst but with a different compositon (SiO2/Al2O3/Na2O = 87.7 : 7.3 : 5.1) and also an offretite/erionite mixed catalyst composed of SiO2/Al2O3/Na2O/K2O = 70.8 : 15.6 : 2.36 : 11.2 revealed that the qualitative effects of reaction temperature, pressure and space velocity were quite similar for all the three catalysts. The offretite/erionite catalyst gave the highest isopropanol yield under comparable conditions and had 2-butene as by products, while the other catalyst had not. It was obvious that catalyst type and composition wielded a great effect on isopropanol synthesis, and the best catalyst of the three studied was the offretite/erionite mixed catalyst.