Influence of surface morphology on the performance of nanostructured ZnO-loaded ceramic honeycomb for syngas desulfurization

FUEL

卷:211

Article

Oh, Wen-Da¹  Lei, Junxi¹  Veksha, Andrei¹  Giannis, Apostolos¹  Lisak, Grzegorz¹  Chang, Victor W. -C.²  Hu, Xiao³  Lim, Teik-Thye^1,4 

[1] Nanyang Technol Univ, NEWRI, Residues & Resource Reclamat Ctr R3C, 1 Cleantech Loop,CleanTech 1, Singapore 637141, Singapore

[2] Monash Univ, Dept Civil Engn, Clayton, Vic 3800, Australia

[3] Nanyang Technol Univ, Sch Mat Sci & Engn, 50 Nanyang Ave, Singapore 639798, Singapore

[4] Nanyang Technol Univ, Sch Civil & Environm Engn, 50 Nanyang Ave, Singapore 639798, Singapore

关键词: Nanostructured ZnO;    ZnO nanosheets;    Honeycomb;    H2S removal;    Syngas;    Gasification;   

DOI  :  10.1016/j.fuel.2017.09.088

来源: Elsevier

【 摘 要 】

A facile seeding-growth protocol was employed to immobilize nanostructured ZnO with nanorod and nanosheet morphologies (ZnO-nR and ZnO-nS, respectively) on cordierite-mullite honeycomb support. By varying the hexamethylenetetramine (HMTA) concentration, Zn precursor, and number of growth cycles during synthesis, different nanorod sizes, nanosheets textures and ZnO layers were obtained. The ZnO-loaded honeycombs were characterized using FESEM, EDX and XRD indicating that the immobilized layer of nanostructured ZnO was highly-crystalline with a thickness of similar to 1 mu m. The synthesized nanostructured ZnO-loaded honeycombs and a commercial ZnO sorbent were applied for removal of sulfur compounds (H2S and COS) from syngas at 400 degrees C. The ZnO-nS showed significantly longer breakthrough time (BTTS) and higher total sulfur sorption capacity (48.7 mg g(-1) ZnO, BTTS = 75.4 min) than the ZnO-nR (9-12 mg g(-1) ZnO, BTTS = 23-25 min) and commercial ZnO sorbent (4.6 mg g(-1) ZnO, BTTS = 6.8 min). The superior sorption capacity of ZnO-nS was attributed to the significantly better surface coverage and higher crystallinity of ZnO nanosheets on the honeycomb. The introduction of additional ZnO nanosheets layers (up to 3 layers) through repeated growth process increased the ZnO loading to similar to 1.5 +/- 0.1 mg mm(-1) (from similar to 0.9 +/- 0.1 mg mm(-1) in the single layer) but resulted in poorer performance (11.6 mg g(-1) ZnO, BTTS = 24.6 min) compared to ZnO-nS. This was due to the increased internal mass transfer resistance and decreased density of the effective reactive sites. The mechanism of ZnO-nS formation is also proposed to provide further insights. Overall, the ZnO-nS showed better regenerability, lower mass transfer resistance, and higher sorption capacity compared to the commercial ZnO and ZnO-nR sorbents indicating that it has a promising potential for syngas desulfurization.

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