Ni-Ti-Ce复合氧化物制备及光热催化CO2还原制合成气性能

Syngas production from photothermal catalytic CO2 reduction over Ni-Ti-Ce composite oxide

摘要:

以六水合硝酸镍、钛酸四丁酯和六水合硝酸铈为原料，采用溶胶凝胶法制备Ni-Ti-Ce复合氧化物催化剂 （Ni-Ti-Ce-S），采用XRD、SEM、EDS、BET、H2-TPR和H2-TPD对Ni-Ti-Ce-S的结构组成、微观形貌、空隙参数和活性物种分布进行表征。将Ni-Ti-Ce-S用于光热协同催化生物质乙醇与温室气体CO2重整（乙醇干气重整，EDR）制合成气反应，对比考察其与传统浸渍法制备的Ni-基催化剂（Ni-Ti-Ce-I）的催化性能，以及其反应条件和稳定性。结果表明，Ni/TiO2-CeO2-S的活性物种NiO和CeO2的平均粒径为17.8和16.8 nm，孔径分布集中在14 nm左右，具有较高的比表面积（14.7 m2/g）和孔体积（0.084 cm3/g），带宽2.45 eV，而Ni/TiO2-CeO2-I的孔径分布集中在16 nm左右，带宽2.78 eV。400 ℃，50 W氙灯光照下，Ni/TiO2-CeO2-S光热协同催化空速35 L/(g·h)的EDR的乙醇转化率为95.91%，高于Ni/TiO2-CeO2-I的85.70%和纯热条件下的80.12%，目标产物n(H2)/n(CO)比值接近于理论值1.0。Ni-Ti-Ce-S高活性与其强金属载体相互作用（SMSI）、活性金属Ni高分散度、高比表面积以及强光吸收能力等因素有关。

Abstract:

The Ni-Ti-Ce composite oxide catalyst (Ni-Ti-Ce-S) was synthesized via the sol-gel method using nickel nitrate hexahydrate, tetrabutyl titanate, and cerium nitrate hexahydrate as precursors. The catalyst"s structural composition, morphology, pore characteristics, and active species distribution were systematically characterized using XRD, SEM, EDS, BET, H?-TPR, and H?-TPD techniques.Ni-Ti-Ce-S was employed for photo-thermal synergistic catalytic reforming of biomass-derived ethanol and greenhouse gas CO? (ethanol dry reforming, EDR) to produce syngas. Its catalytic performance, optimal reaction conditions, and stability were compared with those of a Ni-based catalyst (Ni-Ti-Ce-I) prepared by conventional impregnation.Results indicate that Ni/TiO?-CeO?-S exhibits well-dispersed active species, with average NiO and CeO? particle sizes of 17.8 nm and 16.8 nm, respectively. The catalyst demonstrates a narrow pore size distribution centered at ~14 nm, a high specific surface area (14.7 m2/g), and a pore volume of 0.084 cm3/g, along with a bandgap of 2.45 eV. In contrast, Ni/TiO?-CeO?-I shows a broader pore size distribution (~16 nm) and a larger bandgap (2.78 eV).Under optimized conditions (400 °C, 50 W xenon lamp irradiation, space velocity of 35 L/(g·h)), Ni/TiO?-CeO?-S achieves an ethanol conversion rate of 95.91%, significantly higher than that of Ni/TiO?-CeO?-I (85.70%) and pure thermal catalysis (80.12%). Moreover, the H?/CO molar ratio of the syngas product approaches the theoretical value of 1.0. The superior activity of Ni-Ti-Ce-S is attributed to its strong metal-support interaction (SMSI), high Ni dispersion, enhanced specific surface area, and excellent light absorption capability.