Catalytic Plasma Fischer–Tropsch Synthesis Using Hierarchically Connected Porous Co/SiO₂ Catalysts Prepared by Microwave-Induced Co-assembly

Abstract

Catalytic plasma-enhanced Fischer–Tropsch synthesis (FTS) for gas-to-liquid conversion was investigated using a recently developed novel nanostructured, hierarchically connected micro/meso-porous Co/SiO2 catalyst obtained through microwave irradiation-induced coassembly of the catalyst and catalyst support precursors (Catalysts202010152). This catalyst structure with its micron-scale morphological and chemical heterogeneity is particularly suitable for catalytic plasma reactions. It is shown that a dielectric barrier discharge (DBD) can promote FTS over the catalysts at low temperatures and ambient pressure with 100% conversion without any deactivation over a prolonged time scale (175 h in the current study). In contrast to conventional FTS, the hydrogen conversion is higher in plasma FTS, demonstrating that a DBD can promote FTS for more methane and higher hydrocarbon formation. It is shown that the catalyst is not fully reduced and is a mixture of CoO and Co. Carbon deposition present due to incomplete heat treatment of the catalyst to remove the organic coating on SiO2 support results in catalyst deactivation, which can be eliminated by using high catalyst reduction temperature. Furthermore, the catalytic activity increases during the course of reaction due to the plasma-induced morphological changes in the catalyst structure. In the absence of a plasma, catalyst deactivation is very rapid, which is reversed by burning carbon deposit using DBD plasma in oxygen atmosphere at 150 °C. The results indicate that it is possible to develop a new sustainable, distributed FTS technology operating at low temperatures, ambient pressure, and small scale by optimizing the catalyst property, reactor design, and reaction parameters under plasma conditions.

Recent Advances in Plasma Catalysis

“…22 Akay et al showed DBD coupled with Co/SiO 2 for Fischer−Tropsch synthesis. 23 In both cases, reactant conversions with plasma−catalyst combinations are higher than those with plasma alone or catalyst alone under tested conditions. Song et al placed DBD coupled with HZSM-5 downstream of polyethylene pyrolysis volatiles to generate aromatics-enriched oil and showed product yields are sensitive to plasma conditions.…”

Supported nanocatalysts: recent developments in microwave synthesis for application in heterogeneous catalysis

“…The above sections revealed that a variety of supported nanocatalysts has been prepared by MW assisted methods. The supported nano catlaysts included simple metal catalysts such as Cu, [81][82][83]105,132 Ni, 105,118,136 Co, 105,119,120 Fe, 84 Ru, 85,86,[95][96][97][98][99]141 Ag, 112,116 Au, 112,129,131,142 Pt, [87][88][89][90][91][92]106,111,121,142,145,146 Ti, 122 Zr, 123 Pd, 93,[106][107][108]127,128,130,133,134,…”

“…Some authors even carried out the catalysis reactions under MW reaction conditions over supported nanocatalysts and found fairly good conversion and/or yield. 112,119,120,128,156 The better catalytic activity of MW synthesized supported nanocatalysts can be assumed to be due to improved homogeneous distribution of smaller nanocatalyst particles, larger volume to surface ratio, surface heterogeneity, synergistic interaction between metals as well as stronger interaction between nanocatalyst and support materials. The data on stability of MW synthesized nanocatalyst during recycle is hardly available and more investigation is needed in the area.…”

Imagining Sustainable Human Ecosystems with Power-to-x in-situ Resource Utilisation Technology

“…The selective heating of electrons in a nonthermal plasma generates significant populations of energetic species, enabling lowtemperature activation of stable molecules and alternative pathways to overcome thermodynamically unfavourable reactions [52,[57][58][59]. Incorporating catalyst materials into plasma reactors, known as plasma catalysis (PC), shows significant promise for activating stable molecules such as N 2 and CO 2 and converting them into valuable materials for use in agriculture, transport, and chemical synthesis [13,39,52,[56][57][58][59][60][61][62][63][64][65]. PC processes are attractive for remote applications [57] such as a Lunar or Martian settlement because they are modular and small [57,66], can be cycled rapidly [60,67], are compatible with intermittent power [9,66], and are operated at low temperatures and atmospheric pressure [9,12,13,52,68], eliminating the cost, size, and complexity associated with conventional thermochemical plant equipment.…”