The Role of Zeolite Acidity in Coupled Toluene Hydrogenation and Ring Opening in One and Two Steps
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- 作者：Pedro Castañ ; o ; Barbara Pawelec ; André ; s T. Aguayo ; Ana G. Gayubo ; Jose M. Arandes
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2008
- 出版时间：February 6, 2008
- 年：2008
- 卷：47
- 期：3
- 页码：665 - 671
- 全文大小：270K
- 年卷期：v.47,no.3(February 6, 2008)
- ISSN：1520-5045
文摘
In this work, the effect of HZSM-5 zeolite acidity on hydroconversion of methylcyclohexane and toluene hasbeen studied. These are test reactions for the second step and the single step of aromatic valorization process,respectively, with the aim of obtaining C2+ n-alkanes and isoalkanes. Monofunctional HZSM-5 zeolite catalysts(Si:Al ratio between 15 and 140) have been studied in methylcyclohexane ring opening while bifunctionalcatalysts (hybrid Pt/Al2O3-HZSM-5, same zeolites) have been used in the hydrocracking of toluene. Runshave been carried out in a fixed bed reactor under 250-450 
C and 20-80 bar. A positive effect of HZSM-5zeolite acidity on methylcyclohexane conversion and C2+ n-alkane selectivity is evident at certain conditions,whereas the maximum selectivity to isoalkanes requires an intermediate value of acidity. On the basis of therelationship between conversion and the Si:Al ratio of the HZSM-5 zeolite, the hydrogenolytic cracking ofmethylcyclohexane is proposed as a test reaction to determine the Si:Al ratio. Acidity has a highly favorableeffect in the hydrocracking of toluene given that it avoids the thermodynamic restrictions for toluenehydrogenation and enhancing all the cracking steps during methylcyclohexane (MCH) transformation, whichincreases selectivity to C2+ n-alkanes and isoalkanes.
C and 20-80 bar. A positive effect of HZSM-5zeolite acidity on methylcyclohexane conversion and C2+ n-alkane selectivity is evident at certain conditions,whereas the maximum selectivity to isoalkanes requires an intermediate value of acidity. On the basis of therelationship between conversion and the Si:Al ratio of the HZSM-5 zeolite, the hydrogenolytic cracking ofmethylcyclohexane is proposed as a test reaction to determine the Si:Al ratio. Acidity has a highly favorableeffect in the hydrocracking of toluene given that it avoids the thermodynamic restrictions for toluenehydrogenation and enhancing all the cracking steps during methylcyclohexane (MCH) transformation, whichincreases selectivity to C2+ n-alkanes and isoalkanes.