Jiecheng Zou,Lanxun Zhao,Qiang Hu,Dingding Yao,Haiping Yang
The gasification technology has shown great potential to upcycle plastic waste for clean and high-value fuel. Gasification of disposable plastic masks was investigated in a two-stage pyrolysis-catalytic reforming system, aiming at producing the syngas with flexible H 2 to CO ratio which can be tuned for various downstream applications without further purification and adjustment. To maximize the syngas yield and minimize the carbon deposition, different gasifying agents in the staged catalytic process was explored. The results showed that CO 2 significantly promoted syngas production mainly by increasing CO yield. However, H 2 -rich syngas was obtained via using steam as the gasifying agent. Competitive and synergistic relationships between CO 2 and H 2 O agent at co-feeding process were further revealed. CO 2 facilitated the reforming of H 2 O at low dose of steam while exhibiting a main competition with adequate steam except for synergy at 5 mL/min CO 2 flow rate. An optimum H 2 -rich syngas yield of 135.59 mmol/g plastic with H 2 /CO ratio of 2 was obtained at co-feeding reactants. Therefore, the co-feeding of H 2 O and CO 2 could show positive effect for both coke removal and syngas quality regulation. Results found in this work increased the overall operational flexibility and economy of pyrolysis and catalytic reforming of plastic waste.
Dan Ping,Qingshuo Zhang,Weitao Liu,Shide Wu,Jing Gao,Haoyi Zhang,Shiwen Wang,Huajun Qiu,Shaoming Fang
Electrochemical CO 2 reduction reaction (CO 2 RR) to syngas represents a promising strategy to mitigate CO 2 emission and achieve carbon neutrality. Dual-site metal catalysts have emerged as an effective candidates for syngas production, however, challenges such as limited catalytic activity and inadequate control over the H 2 /CO ratio persist. Herein, a spatially separated dual-site catalyst containing cobalt phthalocyanine (CoPc) and ∼18 nm hollow Co 3 O 4 nanoparticles (NPs) was developed, in which CoPc and Co 3 O 4 are confined outside and inside the N-doped carbon (N–C) support, respectively. Experimental and calculation analyses reveal that the CoPc sites promote CO production, while the Co 3 O 4 NPs are responsible for H 2 production. The strong electronic coupling effect among CoPc, N–C and Co 3 O 4 NPs optimizes the electronic structure of catalyst and modulates the adsorption behaviors of reaction intermediates, leading to superior catalytic performance. A consistent H 2 /CO ratio of 2:1 is achieved across an extensive potential window ranging from −0.6 to −1.1 V vs . RHE, which is highly advantageous for industrial applications. Furthermore, adjustments in catalyst composition and microenvironment enable precise tuning of the H 2 /CO ratio from 1 to 2. This study provides a straightforward approach to designing dual-site catalysts for efficient syngas production.
Building of grain boundary (GB) in Cu-based catalysts has been demonstrated to be an efficient strategy to control the product selectivity of electrochemical CO 2 reduction reaction (eCO 2 RR). However, the fabrication and modulation of GBs in Cu are still challenging. In this study, a series of bare Cu catalysts with controllable density of Cu(111) GBs were investigated systematically for eCO 2 RR. These catalysts exhibit superior eCO 2 RR performance for syngas production with a high FE of ∼80 % and tunable H 2 /CO ratio of 0.46–2.78. Three-dimensional wormlike Cu with abundant (111) GBs displays a stable H 2 /CO ratio of ∼0.5 over a wide potential range from −0.9 to −1.2 V ( vs. RHE). In situ Raman and ATR-SEIRAS spectroscopy combined with DFT calculations reveal that Cu(111) GBs enhance the adsorption of CO 2 , lower the energy barriers of CO 2 to *COOH and *CO, further highlighting the potential to control syngas production with desirable proportion over Cu-based catalysts.
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