Combinatorial neutron imaging methods for hydrogenation catalysts

Abstract

Heterogeneous catalysts are materials with a complex structure at the atomic to mesoscopic scale, which depends on a variety of empirical parameters applied during preparation and processing. Although model systems clarified the general physical and chemical phenomena relevant to catalysis, such as hydrogen spillover, a rational design of heterogeneous catalysts is impeded by the sheer number of parameters. Combinatorial methods and high-throughput techniques have the potential of accelerating the development of optimal catalysts. We describe here a combinatorial approach based on hydrogen adsorption/absorption and hydrogen–deuterium exchange quantified by neutron imaging. The method coined CONI is capable of measuring more than 50 samples simultaneously. As a proof of concept, we study Pt catalyzed WO₃ as an archetypal spillover system, and a Ni-catalyst supported on Al₂O₃ and SiO₂. CONI is ideally suited to distinguish between irreversible surface adsorption and reversible bulk absorption, providing quantitative information. Concretely, CONI yields the number of reversibly adsorbed/absorbed hydrogen atoms in and on a great number of various catalysts in a single experiment.