The chemical conversion of greenhouse gas CO₂ to environmentally benign compounds, especially alternative fuels like methanol, is an inevitable solution to the global warming problem. The intermetallic catalysts exhibit superior catalytic activity compared to the monometallic ones but suffer from loss of activity during the reaction. Herein, we report the influence of the preparation method on the deactivation behaviour of Ga₃Ni₅ catalyst in CO₂ hydrogenation to methanol. The Ga₃Ni₅ catalyst was prepared through three different methods. The spent catalysts from the reactor were characterized by X-ray diffraction, transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX), Brunaue-Emmett-Teller (BET), H₂-pulse chemisorption, and Fourier-transform infrared spectroscopy (FTIR) technique to evaluate the cause and nature of deactivation. After 250 hr of CO₂ hydrogenation, all catalysts had lost about 50% of their initial activity due to the erosion of active sites. The nanoparticle dispersion was found to increase in the order Ga₃Ni₅-CE< Ga₃Ni₅-IWI < Ga₃Ni₅-CP. The activity of catalysts during methanol synthesis (at 473 K, 20 bar) initially depicted a similar trend. However, the selectivity to methanol remained comparatively high for the catalysts prepared by the co-precipitation method. The loss of activity in Ga₃Ni₅ catalysts was mainly attributed to the metal sintering and a lesser extent, by coke deposition. The kinetics of deactivation was studied based on the normalized dispersion, and the deactivation rate constant was estimated using the power-law kinetic rate model. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.

中文翻译：

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金属间化合物Ga-Ni催化剂在CO2加氢制甲醇中的失活行为

将温室气体 CO ₂化学转化为对环境无害的化合物，尤其是甲醇等替代燃料，是解决全球变暖问题的必然选择。与单金属催化剂相比，金属间化合物催化剂表现出优异的催化活性，但在反应过程中会失去活性。在此，我们报道了制备方法对Ga ₃ Ni ₅催化剂在CO ₂加氢制甲醇中失活行为的影响。Ga ₃ Ni ₅催化剂通过三种不同的方法制备。来自反应器的废催化剂通过 X 射线衍射、透射电子显微镜-能量色散 X 射线光谱 (TEM-EDX)、Brunaue-Emmett-Teller (BET)、H ₂脉冲化学吸附和傅里叶变换红外光谱表征光谱 (FTIR) 技术来评估失活的原因和性质。CO ₂加氢250 小时后，由于活性位点的侵蚀，所有催化剂都失去了约50% 的初始活性。发现纳米颗粒的分散以 Ga ₃ Ni ₅ -CE< Ga ₃ Ni ₅ -IWI < Ga ₃ Ni ₅的顺序增加-CP。甲醇合成过程中催化剂的活性（在 473 K，20 bar）最初表现出类似的趋势。然而，共沉淀法制备的催化剂对甲醇的选择性仍然较高。Ga ₃ Ni ₅催化剂的活性损失主要归因于金属烧结，在较小程度上归因于焦炭沉积。基于归一化分散研究失活动力学，并使用幂律动力学速率模型估计失活速率常数。© 2021 化学工业协会和 John Wiley & Sons, Ltd.