Abstract
A bimetallic nickel–molybdenum catalyst supported on γ-alumina was synthesized by the two-step incipient wetness impregnation technique. The activity of the prepared Ni–Mo/γ-alumina catalyst was evaluated in a down flow fixed-bed micro-reactor. In this way, hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions of the main distillate fractions of crude oil were assessed. XRD, SEM, TPR, ICP-OES, BET–BJH and nitrogen adsorption/desorption methods were used for characterizing the synthesized Ni–Mo/γ-alumina catalyst. The active metals with Ni/Mo mass ratio of 0.23 and total metal of 13.7 wt% were loaded on the support, similar to the commercial industrial catalyst. The performance tests were conducted at 3.0 MPa (for light naphtha and heavy naphtha) and at 4.5 MPa (for kerosene and gas oil). The results revealed that the total sulfur conversion of the light naphtha, heavy naphtha, kerosene and gas oil fractions was 98.3%, 95%, 91.7% and 90.1% (after 24 h), respectively.
Highlights
In refineries, crude oil is distilled to various fractions, in which the main distillate fractions including light naphtha, heavy naphtha, kerosene and gas oil are very valuable (Jarullah et al 2011; Prins 2001; Qian et al 2013)
Using a stream composed of 5% H2 in Ar with a flow rate of 40 ml/min, the temperature-programmed reduction (TPR) of each sample was performed for which the Micromeritics TPD-Temperature‐programmed reduction (TPR) 2900 analyzer equipped with a thermal conductivity detector (TCD), heating at a linearly programmed rate of 10 °C/min up to 1000 °C, was employed
With respect to the T.S. conversion, it can be stated that the synthesized catalyst had a relatively high and acceptable performance on heavy naphtha and kerosene, respectively; it had the lowest activity for gas oil, which is due to the larger and more complex molecular structure of the sulfur compounds in the gas oil fraction
Summary
Crude oil is distilled to various fractions, in which the main distillate fractions including light naphtha, heavy naphtha, kerosene and gas oil are very valuable (Jarullah et al 2011; Prins 2001; Qian et al 2013). There are serious regulations, especially in Europe and USA, which limit the impurities in the main petroleum fractions These fractions contain various sulfur and nitrogen compounds that should be removed to help reaching a clean environment (Bassi et al 2015; González-Cortés et al 2006; Ling et al 2009; Rong et al 2014). MoS2 supported over graphene was used for HDS of naphtha for which a simultaneous chemical exfoliation method was followed for preparing the catalyst by which high conversion was obtained (Hajjar et al 2015). In this study, the Ni–Mo/γ-alumina catalyst was synthesized and HDS and HDN reactions on the main distillate fractions including light naphtha (L.N.), heavy naphtha (H.N.), kerosene (Kero.) and gas oil (G.O.) were studied and compared. Experimental ((NH4)6Mo7O24·4H2O) and dimethyl disulfide (DMDS) were supplied by Merck Chemical Co.; analytical grade H 2 and deionized water (DI) were used throughout the experiments
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