Homogeneous versus heterogeneous catalysis

Liu, Y., E. Lotero J. Goodwinjr (2006) A comparison of the esterification of acetic acid with methanol using heterogeneous versus homogeneous acid catalysis. Journal of Catalysis, 242, 278-286,ISSN 00219517. 

Kitanosono T, Xu P, Kobayashi S. Heterogeneous versus homogeneous copper(II) catalysis in enantioselective conjugate-addition reactions ofboron in water. Chem Asian J. 2014 9 179-188. 

In the case of heterogeneous catalysis, a DCKM or microkinetic model must incorporate the added dimension of adsorbed chemical species as well as active versus non-active sites. To obtain the full predictive capability from reactant influent to product effluent, all possible reactions in the system, both heterogeneous and homogeneous, must be accounted for. To properly understand the catalytic reaction sequence, it is possible that seemingly unimportant intermediates on the surface may be what initiate gas phase reactions. To begin this elucidation, the surface chemical species and their properties must be known. 

Figure 3. Catalytic life cycles homogeneous versus heterogeneous catalysis, taking the bulk chemical acrylic acid as an example.

The initial reaction rate of a catalyzed reaction versus the concentration of the substrate [>q (Eq. (9.39), where K, =k, /ki). The catalytic reaction could be homogeneous, heterogeneous or enzyme catalysis so long as it follows the simple catalytic mechanism. The substrate concentration, [X]. at a tate of half the maximum reaction rate, V, I2, defines in Michaelis-Menten enzyme kinetics. 

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