Role of Support in Hydrocracking of n-hexadecane over Sulfided NiMo Catalysts

Abstract

The graphene nanosheets (GNS) have been considered as a support for the synthesis of catalysts applied in various catalytic reactions. In this research, the hydrocracking (HCK) of n-hexadecane as a model component of the long chain paraffin was carried out using synthesized Ni-Mo/GNS and commercial Ni-Mo/Al2O3-SiO2 catalysts in a fixed-bed reactor. The physico-chemical properties of catalysts were determined using XRF, TEM, XRD, TGA and NH3-TPD analysis. The effect of support on the conversion and product distribution in HCK of n-hexadecane was investigated. The stability of the catalysts in the presence of water and coke deposition was examined for the HCK of nonconventional feeds. The obtained results revealed that the active metals were anchored on the functionalized GNS and the stability of Ni-Mo/GNS was significantly increased compared to commercial catalyst. The obtained results indicated that the GNS-supported catalysts have a higher potential for HCK of n-hexadecane in comparison to commercial Ni-Mo/ Al2O3-SiO2 catalysts.

Graphene supported NiMo catalyst: A promising novel hydrocracking catalyst

“…Since acidity is attributed to the support itself and not to the metal phase, the lack of acidity can be related to the impossibility of the NH 3 molecules to be adsorbed on the MoS 2 surface. 10,22 Moreover, the TGA analysis of NiMo catalysts presented in Table 2 verify that the NMFG catalyst significantly yields less amount of coke than the NMAS one under the same reaction conditions. This results and BET adsorption-desorption isotherms of the catalysts confirm that heat and mass transfer of reactants into the pores of NMFG catalyst is facilitated due to its cylindrical structure.…”

“…The preparation method was described in detail in our previous publication. 22 The ammonium heptamolybdate, nickel nitrate, and n-hexadecane (as a feedstock) were purchased from Merck (Darmstadt, Germany).…”

“…Elemental analysis, the temperature-programmed reduction of sulfided catalysts (TPR-S), transmission electron microscopy (TEM) of catalysts, NH 3 -TPD (ammonia temperature-programmed desorption), and TGA analysis were performed according to methods described in our previous publication. 22 Using the elemental analysis, specifications, and properties of raw GNS, synthesized NMFG and commercial NMAS catalysts are revealed and reported in following paragraph. Through TGA analysis of NMAS and NMFG catalysts, oxidation of MoS 2 and NiS 2 species was taken into account to calculate the coke content on the spent catalysts.…”

“…Liquid products of HDC process were recovered and analyzed by gas chromatography (GC) method and described in our previous publication. 22…”

“…The appearance of the former peaks is due to the partial oxidation of the catalyst when it is in contact with air. 10,22 Figures 4B and 4B depict the size distribution of the active NiMo particles, which are determined using the population of the total particles of each NMFG and NMAS catalysts based on data taken from 10 TEM pictures (base on about one hundred particles). Dark spots represent the NiMo particles attached to the surface of GNS and Al 2 O 3 -SiO 2 supports.…”