I like the ref very much, thank you Organikum and Lugh. Those tube furnaces don't look that scary after all.
Here is the second part of the article series:
Deoxygenation of benzoic acid on metal oxides. 2. Formation of byproducts.de Lange, M. W.; van Ommen, J. G.; Lefferts, L.
Applied Catalysis, A: General,
231(1-2), 17-26 (2002). Journal written in English.
CAN 137:142127 ISSN 0926-860X
AbstractBenzene, benzophenone, toluene and benzyl alc. are byproducts in selective redn. of benzoic acid to benzaldehyde on ZnO and ZrO2 catalyst. The pathways to the byproducts are discussed and a complete overview of the reaction network is presented. Benzene and benzophenone are products of the decompn. of the strongly adsorbed benzoic acid at elevated temps. Toluene is formed by deoxygenation of benzaldehyde at O vacancy sites. Direct hydrogenation of benzaldehyde yields benzyl alc. Selectivity to byproducts is not only detd. by the reaction temp., but also by the degree of surface redn. and the difference in adsorption strength between reactant and product. At <360 Deg, benzoic acid forms a benzoate layer which is stable and prevents readsorption of benzaldehyde. Redn. of the catalyst by H leads to a small no. of O vacancy sites which deoxygenate benzoic acid to benzaldehyde, and as a result, selectivity to benzaldehyde is very high (>95%). Higher temps. induce decompn. of the benzoate layer to benzene, and more importantly, enhance the degree of redn. of the catalyst, which results in the formation of toluene from benzaldehyde.