The development of low-cost nickel-based catalysts for direct and selective hydrogenation of 2-butyne-1,4-diol (BYD) to butane-1,4-diol (BAD) under mild conditions is an important and attractive target both in fundamental research and industrialization but remains a formidable challenge. The primary industrial production method for BAD synthesis is a two-step reaction route, which suffers from complicated catalysis conditions and high equipment costs. Herein, we develop a high-performance catalyst via a facile alcohol-treated strategy for highly selective BAD synthesis at moderate operation conditions. The as-synthesized NA-80E catalyst exhibits outstanding BAD selectivity of 98.82% and BYD conversion of 100% at 60 oC and 4 MPa, outperforming most reported results for BAD formation in a one-step process and even being comparable to those obtained by the two-step hydrogenation reaction route under much high temperatures and pressures. Crucially, we found that after facile alcohol (ethanol) treatment, an intriguing phenomenon of suppression of adjacent acid-assisted hydrogenolysis via extra acidic Al species at the NiO-Al2O3 interface is observed, contributing to the precise enhancement of BAD selectivity by inhibiting the production of butanol (BOL). This facile alcohol-treated method along with the revealed mechanism of blocked hydrogenolysis opens vast possibilities for designing high-performance and highly-selective hydrogenation catalysts.

In this work, the variation of the phosphorus content on the surface of vanadium-based bulk catalysts by atomic layer deposition is used to experimentally unravel its catalytic functionality in the selective oxidation of n-butane. The consecutive combustion of maleic anhydride is suppressed, due to a surface enrichment with phosphorus.

Abstract

Vanadium phosphates are established as the benchmark system for the selective oxidation of n-butane towards maleic anhydride. By varying the phosphorus content on the surface of three V-based catalysts with diverse performance, this study experimentally elaborates on the catalytic function of phosphorus. Contact time variation and cofeed studies revealed, that surface phosphates, deposited in sub-monolayers via atomic layer deposition, significantly contribute to an increased product selectivity. Furthermore, our results suggest that the phosphorus particularly suppresses the consecutive combustion of the (re-)adsorbed product. The recently introduced solid solution catalyst V_1-xNb_xOPO₄ with medium maleic anhydride selectivity could be tuned by the surface enrichment with phosphorus towards product selectivities of up to S_MAN=60 %, under optimized alkane-rich feed conditions. Therefore, PO_x-V_0.3Nb_0.7OPO₄ is introduced as promising catalyst, which is not based on vanadyl(IV) pyrophosphate, to access significantly higher MAN formation rates at increased alkane partial pressures of c _n-butane>10 %vol in n-butane oxidation.