Reactivity of OH and hydride species in oxide-catalyzed hydrogenation reactions has attracted great interest. Herein, we report a combined in situ spectroscopic characterization and density functional theory (DFT) calculation study of ceria-catalyzed acetylene semihydrogenation reaction. The ceria surface is fully hydroxylated during the adopted reaction condition. C2H2 adsorbs molecularly on the stoichiometric CeO2 surface and hydrogenates with OH groups selectively to produce C2H4. Semihydrogenation of C2H2 to C2H4 with either OH groups or hydride species on ceria surfaces with surface oxygen vacancies proceeds more facilely than on a stoichiometric CeO2 surface, but C2H4 adsorbs more strongly and further hydrogenates to C2H6 more facilely; moreover, dissociative adsorption of C2H2 to C2H species occurs, which facilely hydrogenates with the hydride species eventually to form C2H6 and react with each other to produce oligomers, decreasing the catalytic selectivity and stability, respectively. These results demonstrate that the ceria catalyst with a stoichiometric surface is extremely selective in catalyzing C2H2 semihydrogenation reaction to C2H4, whereas surface oxygen vacancies or hydride species on ceria are harmful to the catalytic performance.

Selective acetylene hydrogenation is a strongly exothermic process, easy to cause coking and metal agglomeration, and thus leads to deactivation. In this work, Pd/TiO 2 with different oxygen vacancies (V o ) were synthesized by controlling reduction temperature in 300-700 C, in which Pd/TiO 2 -HT300 (HT is reduction temperature) possessed the highest V o content. It was found highly dispersed Pd nanoparticles adjacent to more V o exhibited enhanced catalytic behavior (near 100% conversion at 55 C with 80% selectivity and turnover frequency of 0.12 s À1 ) due to hydrogen spillover generation and electron donation originating from V o sites, confirmed by in situ x-ray photoelectron spectroscopy, in situ Raman, and H 2 -temperature programmed desorption. More importantly, the increasing V o sites trap the released heat and devote to a decrease of heat accumulation over a single active Pd site, and consequently inhibit Pd agglomeration and polymerization, affirmed by high-resolution transmission electron microscopy, CO chemisorption, and thermogravimetric analysis.

The structure sensitivity of CO2 activation in the presence of H2 has been identified by ambient-pressure X-ray photoelectron spectroscopy (APXPS) on Ni(111) and Ni(110) surfaces under identical reaction conditions. Based on the APXPS results and computer simulations, we propose that, around room temperature, the hydrogen-assisted activation of CO2 is the major reaction path on Ni(111), while the redox pathway of CO2 prevails on Ni(110). With increasing temperature, the two activation pathways are activated in parallel. While the Ni(111) surface is fully reduced to the metallic state at elevated temperatures, two stable Ni oxide species can be observed on Ni(110). Turnover frequency measurements indicate that the low-coordinated sites on Ni(110) promote the activity and selectivity of CO2 hydrogenation to methane. Our findings provide insights into the role of low-coordinated Ni sites in nanoparticle catalysts for CO2 methanation.

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Eighteen presented the party's "two hundred years" the ambitious targets, planning to achieve national rejuvenation of the grand blueprint for the people across the country pointed out the direction of struggle, with real passion chasing the dream. The great dream come true, inseparable from the people's support, and personnel training is an important duty of College Counselors. Research based on the country's future development and historical background, focus to achieve "two hundred years" goal, training century talents, cultivating college counselor made five qualities, namely: political literacy, mission accomplishment, age literacy, humanities and law accomplishment. IntroductionAfter the party's 18, our party and state undertakings in various fields gradually opened up new journey, political, economic, military, technological, cultural and other constantly undergoing major changes, new ideas, new ideas, new ideas constantly innovation, impact and Inquiries people's minds. In the economic sphere, the economic development has entered a new normal, continuous reform crucial depth and innovation to create wind and water; in the field of culture, Chinese traditional culture and revitalize, into the heart, to the world, has been a greater carry forward; in science and technology major scientific and technological achievements continue to emerge, attracted worldwide attention; in the realm of ideas, "two hundred years" targeted people in the struggle for the direction, "China dream" has become the common denominator unity universal ideology, socialist core values to get more and more person's identity and practice; in the field of ethics, moral people began to return, continue to carry forward the good and the beautiful, as society gradually goodness, morality Woon, positive energy to get more and more recognition, Chong Yang and dissemination; in areas of social life, people are more concerned about health, concern for the environment, concerned about the world, public-spirited, to maintain the country's image, more and more people talk about the dedication to play, talk about the moral character and so on, these new changes, new fashion, new scenes, vividly to the national people's march " two hundred years "goal in the process, and to achieve lofty goals need Relay generations of struggle, educating people to shoulder responsibility as a college counselor, to focus on cultivating" five kinds of literacy "in order to better contribute to the cause of education. The Realization of "Two Hundred Years" and Cultivate College Counselors Political LiteracyTalent is the country's prosperity and social progress of the determinants in the 21st century is the most precious talent. The party's 18 report planning blueprint for future development of our country, proposed the "two one hundred," the vision, and ultimately achieve this goal without talent, and with the development and growth of more, more people need support, therefore, must be based on college counselors to achieve "two hundred years" goal, cultivate talents c...