SYNTHESIS OF SHORT-CHAIN ALCOHOLS OVER A CS-PROMOTED CU ZNO/CR2O3 CATALYST/

An investigation on the effects of the operating conditions on the hig her alcohol synthesis (HAS) from syngas over a Cs-doped CuZnCr oxide c atalyst has been performed. The effect of temperature, CO/H-2 ratio, s pace velocity and oxygenates, and water addition to the feed stream ha s been studied in order to maximize the short-chain alcohols productiv ity. It has been found that: (i) the reaction temperature is a key-par ameter to control the alcohol productivity, and temperatures in the ra nge 560-585 K are adequate for obtaining high production of C-2-C-3 al cohols. Also, in this temperature range the formation of undesired sid e-products (hydrocarbons) is minimized, (ii) the gradual enrichment of hydrogen in the reactant mixture (in the range H-2/CO = 0.8-1.65) cau ses a progressive increase in the formation of methanol and a decrease in the amounts of C2+ oxygenates, (iii) the product distribution is r ather unaffected by space velocity in the range 9040-15300 Ncc/(h g(ca t)), (iv) the addition of methanol to the CO/H-2 feed stream does not leads to significant variations in the product distribution, (v) the a ddition of ethanol to the feed stream significantly increases the over all C2+ oxygenate productivity, (vi) the results obtained upon ester i njection to the CO/H-2 feed stream are parallel to those obtained upon injection of the corresponding alcohols, i.e. methyl formate and meth yl acetate behave as methanol and ethanol, respectively, (vii) water a ddition does not significantly affect the methanol synthesis reaction, whereas exerts a dramatic inhibitory effect on the formation of the C 2+ Linear and branched alcohols. The observed effect of the operating conditions on the HAS have been discussed in the Light of the thermody namic and kinetic characteristics of the synthesis. (C) 1998 Elsevier Science B.V.