Page 99 - Principles of Catalyst Development
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86 CHAPTER 5
5.2.1. Stoichiometric Analysis
Three tasks are involved in this step. First, all possible stoichiometric
chemical equations are listed. These must be organized in a logical manner,
for example, primary reactant, reactant self interactions, reactant cross
interactions, reactant-products, and product-products. Only those involving
chemically stable compounds are included.
Second, the thermodynamics for each reaction are calculated. The most
useful property is tlG~. T at a specified temperature or range of temperatures.
Computation of tlH? T is also of value but not critical.
Third, types of chemical bond changes are identified for each reaction.
These should be indexed according to some scheme, for example
Dehydrogenation DH
Hydrogenation H
Oxidation 0
Oxygen insertion 0 I
Dehydration OW
Group addition A
Appendix 5 is an extensive compilation of reaction types and is useful in
organizing a systematic nomenclature. For methane oxidation, we have,
among others, the following reactions:
Primary Reactions:
CH 4 = none
O 2 == none
Self Interactions:
2CH 4 = C 2 H 6 + H2 OH 8.5 kcal mole .. 1
= C,H 4 + 2H2 DH 12.8
DH 22.2
= C 2 H 2 + 3H 2
20 2 = hone
Cross Interactions:
CH 4 + ~02 = CH:,OH 01 -20.6
== CH 20 + H2 OI,OH -20.0
= CO + 2H] OI,OH -43.1