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Comparison of cracking and hydrocraking of n ‐heptane on H‐ZSM‐5 catalysts
Author(s) -
Liers Joachim,
Meusinger Josefin,
Reschetilowski Wladimir
Publication year - 1993
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.270160611
Subject(s) - cracking , catalysis , chemistry , bifunctional , hydrogen , zeolite , heptane , bifunctional catalyst , inorganic chemistry , adsorption , platinum , fluid catalytic cracking , organic chemistry
Acid catalyzed cracking and bifunctional cracking of n ‐heptane were investigated on HZSM‐5 catalysts. At a reaction temperature of 543 K, the cracking on metal‐free zeolite was found to be directly proportional to hydrogen partial pressure. Hydrogen influences the hydrogenation of product olefins and carbon deposits and therefore enhances the overall activity. Under the same conditions, in the presence of platinum, the hydrocracking rate reaches a maximum with increasing hydrogen partial pressure. The reaction can be formally described by a Langmuir Hinshewood mechanism: hydrogen is adsorbed on Pt in competition with hydrocarbons. The maximum reaction rate depends on a favourable ratio of the two adsorbed reactants. The energy of activation of hydrocracking was over 100 kJ/mol higher than that of acid cracking.