Effects of particle size on the catalytic performance of MWCNTs supported alkalized MoS₂ catalysts promoted by Ni and Co in higher alcohols synthesis

Abstract

A series of nano‐sized alkalized MoS2 catalysts promoted by Ni and Co supported on multi‐walled carbon nanotubes (MWCNTs) were prepared via the reverse microemulsion technique with water to surfactant (W/S) molar ratios (molwater · mol−1surfactant) of 1–12. All prepared catalysts were extensively characterized by ICP, BET, CO chemisorption, XRD, TPR, and TEM techniques. They were assessed in a fixed‐bed micro‐reactor to find their performance in higher alcohol synthesis from syngas. The results were compared with those of the catalyst prepared by the incipient wetness impregnation method with similar elemental composition. The results showed the relationship of catalyst physicochemical properties and performances to preparation method and average metal particle sizes. Calculated average particle sizes for prepared catalysts via microemulsion showed a decreasing trend with a decrease in W/S ratio. It decreased from 17.4 to 5.26 nm for W/S ratios of 12 to 1, respectively. Similarly, the average particle size for prepared catalysts with the impregnation method was 18.78 nm. The nano‐catalyst prepared via microemulsion with W/S of 1 showed the best performance for CO conversion and higher alcohol selectivity of 66.83 and 37.76, respectively. It was concluded that decreased particle sizes increased the active surface area of the Ni and Co promoted alkalized MoS2/MWCNTs catalysts and increased the fraction of metal particles located inside the CNTs, which in turn improved the catalyst performance.

Support Effects on Water Gas Shift Activity and Sulfur Dependence of Mo Sulfide Catalysts

“…The reduction temperature of Mo–S species in the Mo–S/Al 2 O 3 catalyst increased slightly from 203 to 214 °C after 72 h of WGS reaction. The increased reduction temperature of Mo–S species could be attributed to the increased ordering of the Mo–S species and the onset of crystallization of a Mo–S phase, in good agreement with TEM observations and XRD patterns of the used Mo–S/Al 2 O 3 catalyst shown in Figures and , respectively. The Mo–S species associated with large MoS 2 slabs were previously reported to show low catalytic activity .…”

Activation and deactivation scenarios in a plasma‐synthesized Co/C catalyst for Fischer‐Tropsch synthesis

“…[22] One study has shown that Co catalyst samples with smaller nanoparticles ($5 nm) led to greater CO conversion (66.8 %) with much higher alcohol selectivity (37.8 %) than the samples with larger particles ($17 nm). [32]…”

Nanosheet-structured K–Co–MoS2 catalyst for the higher alcohol synthesis from syngas: Synthesis and activation

“…The composition of the two phases strongly depends on the preparation methods [9] . The common methods for the preparation of alkali modified Co-MoS 2 catalysts include impregnation/coprecipitation methods, reverse microemulsion technique and mechano-chemical activation and so on [6,10,11] . Taking the impregnation as an example, the as-prepared Co-MoS 2 catalyst mainly contained the Co-Mo-S phase if the Co/Mo atomic ratio less than 0.4.…”