In Ukrainian

Abstract

Methanol carbonylation (MC) to produce acetic acid is a strategically important large-scale process (Monsanto and BP Chemicals Cativa TM ), which is carried out under high pressure in the liquid phase using Rh(Ir) catalysts and extremely toxic halide cocatalysts/promoters. In addition to acetic acid, methyl acetate is also an industrially important product of MC. The halogen-free heterogeneous-catalytic process of methanol carbonylation in the vapor phase using catalysts containing no noble metal, in particular Ni-based on carbon supports, provides a number of advantages over homogeneous systems, including the possibility of multifold use of catalytic compositions. Important factors that cause the formation of acetyls are the textural, acidic properties of the catalysts, the presence of modifying/promoting additives in their composition. Nickel and copper chlorides supported on activated carbon were shown in [Catal. Today. 2004. 93–95:451] to catalyze the vapor-phase MC process producing methyl acetate at ambient pressure in the absence of alkyl halides in the gas reaction mixture. This paper presents the results of the studying the effect of supports (activated carbon of BAU-A (AC), SKT, SUGS grades; structured – cordierite, Al 2 O 3 /cordierite) of copper-nickel chloride catalysts, characterized by the low-temperature ad/desorption, XRD, TPD-NH 3 , TPR-H 2 techniques; modifying additives of tin on the production of methyl acetate in the halide-free vapor-phase methanol carbonylation under ambient pressure. It is shown that the yield 18 % of the target product in the presence of a catalyst on activated carbon of the BAU-A grade significantly exceeds the Y MeOAc 3 and 7 % indices for NiCl 2 -CuCl 2 compositions on SKT and SUGS, respectively. The formation of methyl acetate on NiCl 2 -CuCl 2 /AC is facilitated by the optimal combination of the porous structure characteristics (the presence of mesopores with an average diameter of ~ 7 nm) and the surface acidity of the specified catalyst, which are favorable for the activation of reagent molecules of the MC process. Methyl acetate yield of 15 % in the presence of NiCl 2 -CuCl 2 compositions on ceramic honeycomb supports (synthetic cordierite) with a specific surface area ~ 0.5 m 2 /g, commensurate at 355–360 °C with Y MeOAc for NiCl 2 -CuCl 2 /AC, is achieved due to more efficient mass transfer and heat removal in the exothermic reaction of methanol carbonylation compared to highly porous catalysts. The conclusion is substantiated that the modification of the NiCl 2 /AC sample with tin additives provides an increase in the yield of the target product from 2 to 11 %, which may be caused by the formation of intermetallic phase crystallites Ni 3 Sn within NiCl 2 -Sn/AC (identified by XRD) under conditions of catalysis – adsorption/activation sites of CO molecules.