Development of Ni–Mo carbide catalyst for production of syngas and CNTs by dry reforming of biogas

Abstract

Biogas has been widely regarded as a promising source of renewable energy. Recently, the direct conversion of biogas over heterogeneous catalysts for the simultaneous production of syngas and carbon nanotubes exhibits a high potential for full utilization of biogas with great benefits. Involving the combined dry reforming of methane and catalytic decomposition of methane, the efficiency of process is strongly depended on the catalyst activity/stability, mainly caused by carbon deposition. In this study, Ni–Mo catalyst is engineered to provide a life-long performance and perform high activity in the combined process. The surface modification of catalysts by a controlled carburization pretreatment is proposed for the first time to produce a carbide catalyst along with improving the catalyst stability as well as the reactivity for direct conversion of biogas. The performance of as-prepared carbide catalysts is investigated with comparison to the oxide and metallic ones. As a result, the Ni–Mo2C catalyst exhibited superior activity and stability over its counterparts, even though the condensed nanocarbon was largely grown and covered on the surface. In addition, up to 82% of CH4 conversion and 93% of CO2 conversion could remain almost constant at 800 °C throughout the entire test period of 3 h under a high flowrate inlet stream of pure biogas at 48,000 cm3 g−1 h−1. The XPS spectra of catalysts confirmed that the presence of Mo2C species on the catalyst surface could promote the stability and reactivity of the catalyst, resulting in higher productivity of carbon nanotubes over a longer time.

Simultaneous production of syngas and carbon nanotubes from CO2/CH4 mixture over high-performance NiMo/MgO catalyst

“…In addition, Saconsint et al . reported that NiMo can stabilize the crystallite size of MgO at 18.1 nm during the reduction process, while the reduction of MgO showed a larger crystallite size of 24.1 nm 42 .

Figure 2 XRD patterns of NiMo/MgO catalysts: ( a ) calcined and ( b ) reduced catalyst.

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“…The physicochemical properties of as-prepared NiMo/MgO catalyst including elemental composition, crystallinity, and reducibility were analyzed. Table 1 shows the elemental composition of reduced NiMo/MgO catalyst determined by X-ray fluorescence (XRF) and Inductively Coupled plasma (ICP-OES) 42 . It was observed that the total metal loading is 31.8–31.9 wt%, while the mass ratio of Ni to Mo is 0.97–1.07.…”

“… 41 investigated that the addition of 10% Mo raised the catalytic activity and durability of 55% Ni/MgO catalysts when compared to the unmodified catalyst. Besides the use of a second metal to combine their individual advantages, we previously investigated the effect of introducing third metal on the performance of the catalysts and the properties of the synthesized CNTs compare with bi-metallic catalysts 42 . The studies were carried out over NiMo/MgO, CoNiMo/MgO, FeNiMo/MgO, and CoFeMo/MgO.…”

Role of support bio-templating in Ni/Al2O3 catalysts for hydrogen production via dry reforming of methane

“…To evaluate the catalysts’ performance, CH 4 conversion ( ), CO 2 conversion ( ), H 2 yield ( ), and H 2 /CO ratio were calculated using Eqs. ( 2 )–( 5 ), respectively 46 , 47 . …”