Metal-supported catalyst are the cornerstone of many large-scale industrial processes currently used to produce fertilizers, fuels, paints, solvents, pharmaceutical active ingredients, and agrochemicals. The ever-increasing degree of sophistication and control over the metal cluster nanoarchitecture, chemistry, and electronic properties have enabled the development of a wealth of materials with control catalytic selectivity and activity. These metal clusters, however, readily undergo surface reconstruction, poisoning, lixiviation, coking, and sintering in the presence of liquid environments (e.g. aqueous environments). This greatly limits the utilization of these tailored-design model catalysts at the industrial scale. To overcome these limitations, we have developed polymer over-coatings on the catalyst that can act as “co-solvents” to simultaneously; 1) control the selectivity and activity of the catalyst towards the desired product to maximize atom-efficiency of the process, and 2) prevent catalyst deactivation by preventing the sintering, lixiviation, and poisoning. In this contribution we will show the effects of the polymer brush chemistry (poly(N-isopropylacrylamide) and poly(4-vinylpyridine)) on the molecular transport, catalyst selectivity and activity of Pd-supported on non-porous SiO<sub>2</sub> colloidal particles as model catalysts. To evaluate the performance of these catalysts we used as probe reaction the hydrogenation of nitrites in aqueous phase to ammonia and nitrogen, which is a relevant reaction in closing the nitrogen cycle. More broadly, the aim of this research is to develop the designing rules and property-structure-activity-selectivity relationships of hybrid catalysts coated with polymeric brushed covalently attached to the catalyst surface.<br/> <br/>

“Co-solvent” effects induced by polymer over-coatings on metal-supported catalysts for liquid-phase hydrogenation reactions

2019 Fall National Meeting

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