Applied Catalysis A: General ( IF 5.5 ) Pub Date : 2017-08-09 , DOI: 10.1016/j.apcata.2017.08.011 Linh Bui , Aditya Bhan
We report a reaction network detailing the mechanistic origins of 20 C2–C6 byproducts observed during the oxidation of propylene to acrolein at 623 K on a molybdenum-based catalyst promoted with cobalt and nickel used in the industrial production of acrolein. The carbon backbone of propylene is preserved in the sequential oxidation of propylene to allyl alcohol, acrolein, and acrylic acid, as well as propylene oxidation to acetone and propanal via water-mediated pathways. Transient kinetic measurements in conjunction with co-feed experiments of C2 and C3 aldehydes and carboxylic acids show that decarbonylation and decarboxylation reactions, reactions of organic compounds with surface-adsorbed oxygen species, and total combustion reactions are the three mechanisms for CC bond cleavage. CC bond formation reactions that result in C4–C6 byproducts occur via: (i) the addition reaction of a propylene-derived surface allyl species with formaldehyde to form C4 products and with propylene and allyl alcohol to form C6 products, or (ii) the addition reaction of an acrolein (acrylic acid)-derived surface ethenyl intermediate with propylene to form pentadiene and with acrolein to form C5 cyclic oxygenates.
中文翻译:
混合金属氧化物催化剂上丙烯醛生产过程中C C键断裂和形成的机理
我们报告了一个反应网络,详细说明了在以钴和镍促进的钼基催化剂上丙烯在丙烯工业化生产中使用的钼基催化剂上,在623 K下丙烯氧化为丙烯醛过程中观察到的20 C 2 -C 6副产物的机理起源。丙烯的碳骨架保留在丙烯依次氧化为烯丙醇,丙烯醛和丙烯酸的过程中,以及通过水介导的途径将丙烯氧化为丙酮和丙醛的过程中。瞬态动力学测量以及C 2和C 3的共同进料实验醛和羧酸表明脱羰和脱羧反应,有机化合物与表面吸附的氧物种的反应以及总燃烧反应是C C键断裂的三种机理。导致C 4 -C 6副产物的C C键形成反应是通过以下方式发生的:(i)丙烯衍生的表面烯丙基物质与甲醛的加成反应形成C 4产物,与丙烯和烯丙醇的加成反应形成C 6产物, (ii)衍生自丙烯醛(丙烯酸)的表面乙烯基中间体与丙烯加成反应形成戊二烯,与丙烯醛加成反应形成C 5环状含氧化合物。