Performance of Pt-based catalysts in perhydro benzyltoluene dehydrogenation: From semi-batch screening to continuous operation

Standardised semi-batch tests are widely used for catalyst screening in liquid organic hydrogen carrier (LOHC) dehydrogenation. However, literature on their quantitative transferability to continuous reactor operation is scarce. This study investigates the dehydrogenation of perhydro benzyltoluene over three Pt-based (PtRe, Pt and PtS) alumina-supported catalysts in a threephase stirred tank slurry reactor, comparing the results with those from semi-batch tests at comparable operating parameters and degrees of dehydrogenation. Across the investigated temperature range of 210–250 °C, semi-batch operation yielded a substantially higher absolute hydrogen productivity than continuous stirred tank reactor (CSTR) operation, exceeding steadystate values by a factor of three to five. At the same time, the order of catalyst productivity was preserved across reactor concepts: PtRe > Pt > PtS. Logarithmic, ratio and parity analyses revealed that the deviation is systematic rather than random and can be approximated by a reactor dependent empirical transfer factor. However, the degree of quantitative transferability remains catalyst dependent. Apparent Arrhenius analyses revealed comparable activation energies for both reactor concepts but lower pre-exponential factors for CSTR operation. This indicates that the CSTR primarily shifts the attainable rate level rather than the apparent temperature sensitivity. Further, liquid-phase analysis showed that both reactor concepts follow the same primary dehydrogenation pathway. However, continuous operation results in enrichment of the H6-BT intermediate. The results demonstrate that semi-batch screening is suitable for preselecting and ranking catalysts, but evaluating the quantitative process for continuous LOHC dehydrogenation requires reactor specific correction.