| Related citation: | Zhenyu Cheng,Dongdong Feng,Qi Shang,Yijun Zhao,Wenda Zhang,Shaozeng Sun.Mechanism of K/Ni Etching for Biochar-H2O Gasification[J].Journal of Harbin Institute Of Technology(New Series),2024,31(3):1-18.DOI:10.11916/j.issn.1005-9113.2023083. |
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| Author Name | Affiliation | | Zhenyu Cheng | School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Dongdong Feng | School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Qi Shang | School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Yijun Zhao | School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Wenda Zhang | School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China | | Shaozeng Sun | School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China |
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| Abstract: |
| Biomass-H2O gasification is a complex thermochemical reaction, including three processes of volatile removal: homogeneous/heterogeneous reforming, biochar gasification and etching. The rate-determining step is biochar-H2O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni) in the zigzag biochar model. The calculation results show that the gasification of biochar-H2O needs to go through four processes: dissociative adsorption of water, hydrogen transfer (hydrogen desorption, hydrogen atom transfer), carbon dissolution and CO desorption. The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step, which is reduced from 374.14 kJ/mol to 152.41 kJ/mol; the catalytic effect of Ni is mainly reflected in the carbon dissolution step, which is reduced from 122.34 kJ/mol to 84.8 kJ/mol. The existence of K causes the edge to have a stronger attraction to H and does not destroy the π bonds of biochar molecules. The destruction of π bonds is mainly due to the role of H free radicals, while the destruction of π bonds will lead to easier C-C bond rupture. Ni shows a strong attraction to O in OH, which forms strong Ni-O chemical bonds. Ni can also destroy the aromatic structure directly, making the gasification easier to happen. This study explored the catalytic mechanism of K/Ni on the biochar-H2O gasification at the molecular level and looked forward to the potential synergy of K/Ni, laying a foundation for experimental research and catalyst design. |
| Key words: Biochar Potassium-nickel catalysis H2O gasification etching Quantum chemistry Transition state theory |
| DOI：10.11916/j.issn.1005-9113.2023083 |
| Clc Number:TK6 |
| Fund: |
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| Descriptions in Chinese: |
| K/Ni催化生物炭H2O气化刻蚀机理研究 程振宇, 冯冬冬*, 尚琦, 赵义军, 张文达, 孙绍增 （哈尔滨工业大学 能源科学与工程学院 哈尔滨 150001） 摘要：生物质-H2O气化是一个复杂的热化学反应过程，包括挥发分脱除及其均/异相重整、生物炭气化刻蚀3个过程，决速步骤是生物炭-H2O气化蚀刻。本文进行了DFT模拟研究以观察不同金属元素（K/Ni）在锯齿形生物炭模型中的催化作用。计算结果表明，生物炭-H2O的气化需要经历4个过程：水的离解吸附、氢的转移（氢解吸、氢原子转移）、碳的溶解和CO的解吸。能垒表明，降低K活化能的最重要步骤体现在氢转移步骤，从374.14 kJ/mol降低到152.41 kJ/mol；Ni的催化作用主要体现在碳溶解步骤，从122.34 kJ/mol降低到84.8 kJ/mol。K的存在使边缘对H具有更强的吸引力，并且不会破坏生物炭分子的π键。π键的破坏主要是由于H自由基的作用，而π键的损坏会导致C-C键更容易断裂。Ni对OH中的O表现出强烈的吸引力，从而形成强烈的Ni-O化学键。镍还可以直接破坏芳香结构，使气化更容易发生。本研究从分子水平探讨了K/Ni对生物炭-H2O气化的催化机理，并展望了K/Ni的潜在协同作用，为实验研究和催化剂设计奠定了基础。 关键词：生物炭；钾镍催化；H2O气化刻蚀；量子化学；过渡态理论 |
