Studies On Propionic Acid Preparation By Vapor Phase Carbonylation Of Ethanol Over Nickel-Based Catalyst

As an important fine chemical product, propionic acid is well known as one of the most economical, effective, and safest food preservative, which is extensively applied in antisepsis and preservation for corn, feedstuff and food. The process of propionic acid production by vapor phase carbonylation of ethanol has such advantage as low pressure, low temperature, low cost and no pollution.In this paper, the supported Ni-Cu bimetal catalyst for the carbonylation of ethanol was studied in a fixed micro-reactor by orthogonal experiments. The effects of Ni loading, Cu loading and calcinations temperature on the performance of the catalyst were measured, and the optimal conditions for the catalyst preparation were concluded.The process conditions for vapor phase carbonylation of ethanol were systematically investigated for the first time in this paper. In addition, the analysis approaches for products were made, by which the components in products were exactly analyzed by GC-MS.By experiments, the process conditions for vapor phase carbonylation were optimized as that reaction pressure was 0.2MPa, reation temperature was 250℃, the molar ratio in the feedstock was n(CO):n(EtOH):n(EtI)=10:5:1, and the space velocity of liquid ethanol was 1.56h-1.The results of stability tests indicated that there was a induction period in the vapor phase carbonylation of ethanol, in the beginning 2 hours, while the catalyst behaved a low activity, but the activity rapidly increased to a top value in the next 2 hours, then it went a little down and tended to stabilization; the catalyst performed a steady performance without descending trend in the 60 hours test with 86% ethanol conversion and 90% propionic acid selectivity.The results of TPR experiments showed that NiO and CuO were dispersed well on the surface of active carbon and the abilities for reduction of them were strengthened, the proper reduction temperature was 550℃. The BET surface area of the catalyst were measured. XRD experiments indicated that NiI2 and Cu(OH)2 were generated in the catalyst, and explained the phenomenon of the existence of the induction period during the vapor phase carbonylation of ethanol.