Direct conversion of syngas to DME over CuO-ZnO-Al₂O₃/HZSM-5 nanocatalyst synthesized via ultrasound-assisted co-precipitation method: New insights into the role of gas injection

Abstract

SUMMARYIn this study, direct synthesis of dimethyl ether (DME) is conducted over a bifunctional CuO-ZnO-Al 2 O 3 /H Zeolite Socony Mobil-5 (HZSM-5) nanocatalyst. A hybrid method of ultrasound-assisted co-precipitation is used for the synthesis of catalysts, and the effect of gas injection during sonication is investigated. The physicochemical characteristics of the catalysts are analysed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), particle size distribution (PSD), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET) and Fourier-transformed infrared (FTIR) methods. In the absence of gas injection, the acetate-based catalysts have a better morphology and higher surface area than the nitrate-based catalyst. Gas injection significantly changes the morphology and structural properties of the acetate-based catalyst. High surface area, narrow PSD and better dispersion of small CuO crystals are obtained in a gas-injected synthesized sample. DME synthesis experiments showed that the CO conversion and DME selectivity are correlated with surface area, nanocatalyst particle size and its dispersion. The gas-injected CuO-ZnO-Al 2 O 3 /HZSM-5 nanocatalyst that has the highest surface area and the smallest dispersed particles showed more than 70% DME selectivity. The gas-injected CuO-ZnO-Al 2 O 3 /HZSM-5 nanocatalyst exhibited high stability in terms of CO conversion and DME yield over 1440-min time on a stream test at 275°C, 40 bar and 18 000 cm 3 g.h À1 .

Preparation of a hydrophobic-hydrophilic adjustable catalyst surface for the controlled synthesis of polyoxymethylene dimethyl ethers: A potential replacement of diesel fuel

“…One is that the improvement of hydrophobicity of solid acid catalyst promotes the conversion of methylal and formaldehyde to PODE 2 and further polymerization reaction. PODE [2][3][4][5] selectivity was enhanced with the increase of dichlorodiphenylsilane content. Thus, the consumption of methylal leads to breaking the reaction equilibrium of methanol and formaldehyde to methylal and improvement of methanol conversion.…”

“…Thus, the modified catalysts with dichlorodiphenylsilane exhibited higher performance in the target product selectivity. PODE [2][3][4][5] selectivity was enhanced with the increase of dichlorodiphenylsilane content. We can also conclude that the hydrophobic treatment can change the product distribution of methanol and formaldehyde aqueous solution to PODE.…”

“…1 Growing interest is recently being shown in oxygencontaining fuels because they could reduce the environmental pollution that is caused by the automobile engine. [2][3][4] Polyoxymethylene dimethyl ethers (PODE) with the formula CH 3 O-(CH 2 O) n -CH 3 (n ≥ 2) are a kind of ether without carbon-carbon bonds. 5,6 With high cetane number and high oxygen content, PODE is an emerging clean fuel and shows a significant performance to improve combustion efficiency for the diesel engine.…”

Waste to liquid fuels: potency, progress and challenges

“…Gasoline range hydrocarbons (i.e., light hydrocarbon components) are normally produced using Iron (Fe)‐based catalysts at temperatures ≥300 ° C. Catalysts based on Cobalt (Co) are commonly employed at low reaction temperatures for the production of longer chain/heavier hydrocarbons (i.e., in the diesel and wax range). According to Allahyari et al and Bin et al , bifunctional catalysts like CuO–ZnO–Al 2 O 3 /H‐ZSM‐5 can produce high yields (>70%) of dimethyl ether from syngas at temperatures lower than 300 ° C. Modification of the reaction parameters such as catalyst compositions, temperature, syngas ratio, and pressure is therefore very critical in deriving specific liquid fuel components. Distillation process is usually accomplished to separate the various fuel components derived from the reaction.…”

Sustainable synthesis of supported metal nanocatalysts for electrochemical hydrogen evolution

“…In recent decades, considerable efforts have been devoted to enhancing catalytic performance of SMNCs by modulating and optimizing their size, shape, composition and structure, among other parameters [15][16][17][18][19][20]. Accordingly, various SMNCs have been developed via numerous traditional methods, such as precipitation [21][22][23][24][25][26][27], sol-gel [28][29][30][31][32], solvothermal [33][34][35][36][37][38], and high temperature pyrolysis [39][40][41][42][43][44] (Fig. 1(b)).…”