Morpholine-modified Pd/γ-Al2O3@ASMA pellet catalyst with excellent catalytic selectivity in the hydrogenation of p-chloronitrobenzene to p-chloroaniline

Abstract

An amino poly (styrene-co-maleic anhydride) polymer (ASMA) encapsulated γ-Al2O3 pellet material has been synthesized successfully. After loading with Pd species and modified with morpholine, the inorganic-organic hybrid material shows an excellent catalytic property in the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). In this procedure, morpholine can connect with the polymer layer in a form of amide bond and acts as an unparalleled immobilized dechlorination inhibitor, which can avoid further dechlorination efficiently and keeps stability due to the repulsive effect from the surviving C-O-C bond. The catalyst as prepared was characterized by using XRD, TGA, SEM, TEM, FT-IR, and ICP-OES, and it was further tested in the selective hydrogenation of p-CNB. It shows a supreme catalytic activity (almost 100%) and selectivity (up to 99.51%) after recycling for even 10 times, much superior to the blank alumina supported palladium (47.09%).