Syngas conversion into light hydrocarbons over bifunctional catalyst: Effect of the density of contact between Cu-ZnO-Al2O3 and SAPO-34

A series of hybrid catalysts with different catalytic bed dispositions (layer bed and simple random mixture) of Cu-ZnO-Al2O3 and SAPO-34 have been adopted and evaluated in syngas conversion into light C2-C4 hydrocarbons. An effect of the proximity between the two solids on the CO hydrogenation activity was demonstrated. A sphere contact quantification model was developed to estimate the concentration of contact between them for any simple random mixture. Comparing the evolution of gain of CO conversion (or hydrocarbon yield) with the theoretical results, it was shown that the density of contact was identified as the key factor for the catalytic performances (contact-activity relationship). Finally, the knowledge of the contact morphology, determined by FEG-SEM, allowed proposing the NH3-TPD as method characterizing the concentration of contact.