The development of improved catalysts for the hydrogenation of CO₂ into methane is a sustainable response to the energy crisis and environmental problems at the global level. Mn‐Ce/N‐TiO₂ heterojunctions, comprising a Mn‐Ce concretion composite, were prepared using a sol–gel technique, and the photocatalytic hydrogenation of CO₂ was studied using visible light as alternative driving energy. The photocatalyst composite was characterized, and synergistic effects on the photocatalytic hydrogenation of CO₂ into methane were investigated. The characterization results confirmed that there was a considerable shifting of band‐gap energy towards the visible range with required properties, which enhances photocatalytic activities under natural sunlight. Carbon dioxide hydrogenation and its potential for conversion into methane was evaluated using a specially designed photoreactor and different light sources. The results show a CO₂ hydrogenation rate of about 16.8% ±0.2 in a visible light‐assisted catalytic reduction process in 60 min. The irradiation time and light source were studied and significant impacts on CO₂ hydrogenation were observed under a LED light source and with H₂O vapor as a reducing agent (up to 23.4% ± 0.2). The effect of photocatalysis on the methane yield in the anaerobic digestion (biomethanation) process was evaluated and a potential methane yield of up to 13.5% within 24 h was observed. The results suggested promising and sustainable applications of the Mn‐Ce/N‐TiO₂ heterojunction composite for CO₂ hydrogenation and for the conversion of CO₂ into fuel and methane in the biomethanation process. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd

中文翻译：

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轻松合成Mn-Ce / N-TiO2复合材料以将CO2加氢成甲烷并提高生物甲烷化反应中的甲烷收率

研发用于将CO ₂加氢为甲烷的改良催化剂是对全球能源危机和环境问题的可持续回应。使用溶胶-凝胶技术制备了包含Mn-Ce固结复合材料的Mn-Ce / N-TiO ₂异质结，并使用可见光作为替代驱动能研究了CO ₂的光催化加氢。对光催化剂复合材料进行了表征，并对CO ₂的光催化加氢具有协同作用。对甲烷进行了调查。表征结果证实，带隙能量在具有所需特性的可见光范围内有相当大的偏移，从而增强了自然阳光下的光催化活性。使用专门设计的光反应器和不同的光源评估了二氧化碳的氢化作用及其转化为甲烷的潜力。结果表明，在可见光辅助的催化还原过程中，在60分钟内，CO _2的氢化率约为16.8％±0.2。研究了辐照时间和光源，观察了在LED光源和H ₂下对CO ₂加氢的显着影响。O蒸气作为还原剂（最高23.4％±0.2）。在厌氧消化（生物甲烷化）过程中，评估了光催化作用对甲烷产率的影响，并观察到24小时内甲烷潜在产率高达13.5％。结果表明，Mn-Ce / N-TiO ₂异质结复合材料在生物甲烷化过程中用于CO ₂加氢以及将CO ₂转化为燃料和甲烷的应用前景广阔且可持续。©2020年化学工业协会和John Wiley＆Sons，Ltd