| Summary: | 碩士 === 國立中正大學 === 化學工程研究所 === 86 === At the past research we found that Pd/SDB(Styrene divinyl benzene
copolymer) can directly transfored ethanol (contained 7.52% H2O) to ethyl
acetate(ethanol conversion 40%﹐ethyl acetate selectivity 54%﹐acetic
acid selectivity 37%)by one step. But ,because of the interaction between
metal and hydrophobic support are so week﹐palladium and the
intermediate products,acetic acid, easily to become Pd(CH3COO)2,and
induced metal extraction(metal extraction 50%).With improved metal
extraction﹐we used Y-Zeolite as our support﹐using bifunctional
catalysis to eliminate acetic acid selectivity. Otherwise﹐the interaction
between metal and support is greatly improved by using Y-Zeolite
support﹐and eliminate metal extraction(metal extraction <0.1%).From
EXAFS data analysis of our fresh and used catalyst, we know, because the
H2O adsorbed on the surface of catalysts and then it interacted with Pd
clusters to form PdOH2, and then metal agglomeration which was induced
by water poisoning, and then catalysts deactivated. So we add Amberlyst
35 in the Pd/SDB system, using the hydrophobic property to prevent metal
agglomeration from water poisoning: and eliminate the contact time
between acetic acid and catalyst. Therefor we can eliminate the metal
extraction in the Pd/SDB system. In the research we found, the ratio
between Amberlyst35 and Pd/SDB have greatly relation to ethanol
conversion, ethyl acetate selectivity, acetic acid selectivity, and metal
extraction. When the ratio between Amberlyst35 and Pd/SDB equal to
0.4/1, it''s the optimum mixer condition to operate.(ethanol conversion
46%,ethyl acetate selectivity 74%,acetic acid selectivity 17%,metal
extraction<1%). But at the higher ratio between Amberlyst35 and
Pd/SDB(4/1), there are no better performance(ethanol conversion 50%,
ethyl acetate selectivity 77%,acetic acid selectivity 17% metal extraction
2%). At the other side, we used higher ratio of Si /Al catalyst, as
hydrophobic support, to prevent metal agglomeration and eliminate metal
extraction; and the result is matched our goal(ethanol conversion 31%,ethyl
acetate selectivity 63%,acetic acid selectivity 25%,metal extraction<1%).
But at higher temperature we found: ethanol will dehydrate to form
ethylene , and then ethylene polymerized to become coke. Coke will
occupied the active site, and then catalyst deactivated.
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