Study of the Rod-Like and spherical nano-ZnO morphology on H2S removal from natural gas

The purpose of this work is to study the adsorption of H2S from gas streams containing He and CH4 with an emphasis on the influence of the sorbent morphology on the process of adsorption. As an example of the approach, a unique modified nano-ZnO sample with a Rod-like morphology was fabricated and comparatively studied together with a nano-spherical ZnO sample under various conditions. The objective was accomplished applying central composite design (CCD) in order to screen the effects of significant adsorption parameters obtained by Placket-Burman design. Morphology of the sorbent, temperature, space velocity and H2S feed concentration were initially evaluated. Placket-Burman design experiments showed a wide deviation of adsorption capacity of 0.03-0.24 g H2S/g ZnO. Results indicated that comparing other parameters Rod like morphology comparing spherical, had significant effect on all four independent H2S adsorption parameters. Besides that, space velocity and H2S feed concentration were found to be effective parameters on adsorption of hydrogen sulfide in the range of 4000-8000 h−1 and 0.5-1 mol% respectively. Moreover, experiments revealed a negligible effect of adsorption temperature in range of 150-250 °C. The optimized condition obtained a dynamic capacity of 0.2401 g H2S/g ZnO at space velocity 4000 h−1 and H2S feed concentration of 1 mol%. Proceeding our study by significant parameters, analysis of variance (ANOVA) displayed a high coefficient of determination (R2) value of 0.931-0.959, indicating the satisfactory adjustment of the quadratic model.