Directional Catalytic Hydroconversion of Oxybis (methylene)dibenzene and an Extract from Piliqing Subbituminous Coal over a Magnetic Difunctional Solid Superbase

Abstract

AbstractAn active and novel magnetic difunctional solid superbase catalyst Ni‐Mg2Si/attapulgite powder (AP) was prepared by thermally decomposing nickel tetracarbonyl onto the as‐synthesized Mg2Si/AP followed by impregnating Mg2Si onto AP in CCl4 and characterized by multiple analyses. It was also successfully used in the catalytic hydroconversion (CHC) of coal‐related model compound oxybis (methylene) dibenzene (OBMDB) and an extract (E) from Piliqing subbituminous coal (PSBC) in n‐hexane. As a result, OBMDB was completely converted to methylcyclohexane by the CHC under 3 MPa of initial hydrogen pressure at 240 °C for 2 h. Ni‐Mg2Si/AP can activate H2 to biatomic active hydrogen (H…H) and split H2 to immobile H+ attached on the Ni‐Mg2Si/AP surface and relatively mobile H−. Then the bridged linkage (BL) in OBMDB can be cleaved by H− attack on a α‐carbon atom in OBMDB, producing toluene and benzyloxy anion, which abstracts H+ from the Ni‐Mg2Si/AP surface to afford phenylmethanol (PM). The α‐carbon in PM is attacked by H‐ to generate toluene and HO−. H…H transfers to benzene ring in toluene yields methylcyclohexane. The soluble portion (SP) from the CHC (SPE‐CHC) and non‐CHC (NCHC) (SPE‐NCHC) of E were analyzed with a gas chromatograph/mass spectrometer and Fourier transform infrared spectrometer. Non‐substituted cycloalkanes (NSCAs) are predominant in the SPE‐CHC, accounting for 66.9 % of the total group components, and interestingly 65.3 % of NSCAs is cyclohexane, while non‐substituted arenes are the most abundant in the SPE‐NCHC. The results indicate that the CHC is beneficial to the fracture of COCBB and hydrogenation of ARs to produce more NSCAs.