负载Ir单原子和团簇的α-MoC催化剂用于高效催化CO_(2)加氢制CO

在高温逆水气变换(RWGS)反应中,开发高活性和高稳定性的金属负载型催化剂还存在巨大挑战。针对此问题,本研究采用溶液蒸发自组装法构建了Ir物种负载于α-Mo C的协同催化剂,结果表明,Ir与α-Mo C的协同效应使其在较宽的温度范围内均有较好的RWGS反应性能。特别是在500℃、0.1 MPa、300000 mL·g^(-1)·h^(-1)的反应条件下,0.5%Ir/MoC催化剂的CO_(2)转化率高达48.4%,接近CO_(2)平衡转化率(49.9%),同时,CO选择性和CO时空收率分别高达94.0%和423.1μmol·g^(-1)·s^(-1),且在100 h之内反应性能几乎没有衰减,具有优异的高温稳定性,此催化性能也超过了大多数文献报道。系列结构表征表明,Ir物种均匀地分散在α-Mo C载体上,其电子较利于转移至α-Mo C而形成金属载体强相互作用,极大地提高了催化稳定性;同时,当Ir负载量高于0.2%(质量分数)时,Ir团簇(Irn)和Ir单原子(Ir1)同时存在,与α-MoC形成了Irn-Ir1-C-Mo协同位点。其中,0.5%Ir/Mo C催化剂拥有较小尺寸的Irn和较多的Ir1,显著地促进了CO_(2)和H2的吸附和活化,并促进了甲酸盐中间体的生成和解离,从而获得了优异的RWGS性能。这项工作为设计和制备高效稳定的CO_(2)利用催化剂提供了一定的参考和指导。

以类水滑石为前驱体的Cu/ZnO/Al_(2)O_(3)催化剂用于CO_(x)加氢合成甲醇:CO在反应混合物中的作用

近年来,催化CO_(2)加氢合成甲醇被视为有望解决温室效应和燃料枯竭的有效途径。目前,铜基催化剂因具有较高的反应活性被广泛应用于工业生产。然而,竞争逆水煤气变换反应产生的CO导致甲醇选择性较低,同时副产物水引起Cu发生不可逆烧结,进而降低甲醇产率。众所周知,CO能够调整分子的表面竞争吸附和活性位的氧化还原行为,本工作拟向原料气中掺入具有还原性的CO以抑制逆水煤气变换反应和防止表面氧化中毒。另一方面,通常认为铜基催化的CO_(2)加氢制甲醇是结构敏感性反应,不同的前驱体能够显著影响催化剂结构和形貌,进而影响催化活性。因此,我们首先通过共沉淀法和蒸氨法制备了含有类水滑石前驱体(CHT-CZA)和复合物前驱体(CNP-CZA)结构的Cu/ZnO/Al_(2)O_(3)催化剂。随后,为探究CO掺杂后反应机理,在250℃,5 MPa的反应条件下,含有不同比例CO的原料气中(CO_(2):CO:H_(2):N_(2)=x:(24.5−x):72.5:3)评价两种催化剂对甲醇合成的性能。评价结果显示两种催化剂反应性能趋势相同,随着CO含量增加,CO_(2)转化率和STY_(H2O)不断降低,STY_(MeOH)逐渐增加。X射线光谱(XPS)显示随CO含量增加,催化剂表面还原性Cu比例增加。评价和表征结果说明CO引入抑制了逆水煤气变换反应的发生,通过还原被H_(2)O氧化的活性Cu表面,促使更多的活性Cu位点暴露参与甲醇合成。另一方面,透射电镜(TEM)显示掺杂的CO会过度还原而引起颗粒团聚,导致催化剂逐渐失活。相比之下,含有水滑石前驱体的催化剂在任何气氛下均表现出更加优越的反应性能和长周期稳定性。这可归因于类水滑石前驱体独特的片层结构通过结构限域作用有效避免了因CO过度还原而导致的金属颗粒团聚,从而减少活性位点损失。

Reduning Injection prevents carrageenan-induced inflammation in rats by serum and urine metabolomics analysis

Objective:To elucidate the anti-inflammatory mechanism of Reduning Injection(RDN)by analyzing the potential biomarkers and metabolic pathways of the carrageenan-induced inflammatory model from the overall metabolic level.Methods:Rat inflammatory model was established by carrageenan.UPLC-Q-TOF/MS was used to detect and analyze changes of endogenous metabolites in the serum and urine of carrageenan-induced inflammatory rats.Combined with multivariate analysis and databases analysis,inflammatory-related potential biomarkers were screened and identified to analyze possible metabolic pathways.The reliability and biological significance of these biomarkers was verified by metabolic network analysis and correlation analysis with pharmacodynamic indicators.Results:A total of 16 potential biomarkers were screened and identified by multivariate analysis and metabolite databases,among which 13 species could be adjusted by RDN.The metabolism pathway analysis revealed that histidine metabolism,sphingolipid metabolism,and tyrosine metabolism were greatly disturbed.Their biomarkers involved urocanic acid,sphingosine,and norepinephrine,all of which showed a callback trend after RDN treatment.The three biomarkers had a certain correlation with some known inflammatory-related small molecules(histamine,arachidonic acid,Leukotriene B4,and PGE2)and pharmacodynamic indicators(IL-6,IL-1β,PGE2and TNF-a),which indicated that the selected biomarkers had certain reliability and biological significance.Conclusion:RDN has a good regulation of the metabolic disorder of endogenous components in carrageenan-induced inflammatory rats.And its anti-inflammatory mechanism is mainly related to the regulation of amino acid and lipid metabolism.This research method is conducive to the interpretation of the overall pharmacological mechanism of Chinese medicine.