The Preparation Of Highly Dispersive Supported Nickel Catalyst For Arene Hydrogenation

Catalytic hydrogenation of arenes, a crucial subject for using heavy carbon resources, centeron highly active supported metallic catalysts, which usually contain nickel as the main catalyticactive substance. Ni(CO)4(NTC) directly decomposes to highly dispersive nickel when elevatedtemperature, however, it is extremely difficult to decompose it onto supports stably due to its toolow volatilization temperature. Herein, NTC was used as the precursor for nickel and then it wasdissolved into diethyl ether mixed with ZSM-5zeolite in an autoclave. After in-situdecomposition of NTC at relative low temperature, a catalyst, nickel supported by ZSM-5(i.e.Ni/ZSM-5), was prepared easily and efficiently. A series of characterizations for Ni/ZSM-5wereperformed, i.e. Inductively coupled plasma optical emission spectrometer (ICP-OES), Scanningelectron microscopy (SEM) with Energy dispersive spectroscopy (EDS), High resolutionelectron microscope (HREM), X-ray diffraction (XRD), H2temperature programmed reduction(H2-TPR), NH3temperature programmed desorption (NH3-TPD), X-ray photoelectronspectroscopy (XPS) and BET method (BET). The load of the nickel was equivalent to themetallic load of supported noble metal catalysts. Nickel supported by ZSM-5was amorphousstate, greatly improving the effective area for catalyzing. Interacting with the support strongly,nickel reacted with the acidic groups on the ZSM-5to be stronger acidic groups of electrondeficiency. The specific surface area of ZSM-5declined and the mesoporous was partiallyblocked after supporting nickel, indicating NTC mainly decomposed on the surface of ZSM-5and was partially impregnated into the mesoporous of the support.Compared with the catalyst prepared via the traditional ‘impregnation-reduction’, theNi/ZSM-5showed a higher activity to catalyze arene hydrogenation. Catalyzed by the Ni/ZSM-5,benzene, toluene, naphthalene, durene, anthracene and phenanthrene were all hydrogenatedcompletely. The catalyst could be recycled for several times and it was passivated due to theagglomeration of supported nickel or the carbon deposit caused by long-time catalyzing reactionat high temperature. Because of biatomic hydrogen transfer, cis-products were predominant aftercondensed arenes hydrogenated, which was further proved via the catalytic hydrogenation of9,10-diphenylanthracene. At last, the Ni/ZSM-5was used to catalyze the hydrogenation of heavymixture from ‘methanol to gasoline’, low-temperature and high-temperature coal tar, respectively.All the three industrial oils were greatly upgraded and all arenes in the heavy mixture, majorityof arenes in the low-temperature coal tar and most of the arenes in the high-temperature coal tarwere completely saturated.