TPR Investigation of bimetallic Ru-Cu samples supported on SiO 2 , Al 2 O 3 and MgO

Bimetallic Ru-Cu samples supported on SiO 2 , Al 2 O 3 and MgO were studied by the temperature-programmed reduction (TPR) technique. Experiments were carried out both on unreduced impregnated salts and after oxidation of already reduced samples. The TPR profiles reveal a simultaneous reduction of ruthenium and copper precursors, even though the Ru and Cu in the monometallic catalysts exhibit reduction peaks which differ by up to 150 °C. It is suggested that the two metal salts interact during the stages of preparation and drying, and after reduction form bimetallic aggregates which are not stable and tend to separate. The stability of the bimetallic particles was found to be strongly dependent on the support used, being higher on SiO 2 than on Al 2 O 3 and MgO. It is suggested that the chemical nature of the support determines the different degree of interaction and/or agglomeration of the bimetallic particles. Auf SiO 2 , Al 2 O 3 und MgO aufgebrachte bimetallische Ru-Cu-Proben wurden mittels temperaturprogrammierter Reduktion (TPR) untersucht. Experimente wurden sowohl mit unreduzierten, durch Impregnation aufgebrachten Salzen als auch mit nach vorangegangener Reduktion reoxydierten Proben ausgeführt. Die TPR-Profile lassen eine gleichzeitige Reduktion der Ruthenium- und Kupfervorstufen erkennen, obwohl Ru und Cu in monometallischen Katalysatoren Reduktionspeaks zeigen, die um bis zu 150 °C voneinander entfernt liegen. Es wird angenommen, daß die zwei Metallsalze während des Darstellungs- und Trocknungsstadiums miteinander in Wechselwirkung treten und nach der Reduktion nicht stabile, zum Zerfall tendierende bimetallische Aggregate bilden. Die Stabilität der bimetallischen Partikel ist stark vom Träger abhängig, sie ist an SiO 2 höher als an Al 2 O 3 und MgO. Es wird angenommen, daß die chemische Natur des Trägers den Grad der Wechselwirkung und/oder Agglomeration der bimetallischen Partikel bestimmt. Методом температурн о-программного восстановления (ТПВ) и зучены биметаллические обр азцы рутений — медь на подложках из двуокиси кремния, о киси алюминия и окиси магния. Экспер именты были проведен ы как с невосстановленными пропитанными солями, так и с вновь ок исленными ранее восстановленными об разцами. Профили крив ых показывают одноврем енное восстановлени е рутения и меди, тогда как в случа е монометаллов пики восстановления рутения и меди отлича ются на 150 °C, Это свидетельствует о том, что соли обоих металлов взаим одействуют между соб ой на стадии получения и высушива ния, а после восстановления обра зуют биметаллически е агрегаты, которые неустойчивы и имеют тенденцию к разделению. Установ лено, что стабильност ь биметаллических час тиц сильно зависит от характера подложки, я вляясь более высокой на двуокиси кремния по сравнению с тем, что на окиси алюминия и окис и магния. Предположен о, что химическая природа п одложки определяет различную степень вз аимодействия или агл омерации биметаллических час тиц.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43142/1/10973_2005_Article_BF01912699.pd

Identification of active sites on supported metal catalysts with carbon nanotube hydrogen highways

Catalysts consisting of metal particles supported on reducible oxides exhibit promising activity and selectivity for a variety of current and emerging industrial processes. Enhanced catalytic activity can arise from direct contact between the support and the metal or from metal-induced promoter effects on the oxide. Discovering the source of enhanced catalytic activity and selectivity is challenging, with conflicting arguments often presented based on indirect evidence. Here, we separate the metal from the support by a controlled distance while maintaining the ability to promote defects via the use of carbon nanotube hydrogen highways. As illustrative cases, we use this approach to show that the selective transformation of furfural to methylfuran over Pd/TiO2 occurs at the Pd-TiO2 interface while anisole conversion to phenol and cresol over Cu/TiO2 is facilitated by exposed Ti3+ cations on the support. This approach can be used to clarify many conflicting arguments in the literatureWe acknowledge financial support from the National Science Foundation, Grant CAREER1653935. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. E.C.W. and J.T.M. were supported in part by Center for Innovative Transformation of Alkane Resources (CISTAR) by the National Science Foundation under Cooperative Agreement No. EEC-1647722. Open access fees fees for this article provided whole or in part by OU Libraries Open Access Fund.Ye

Catalysing sustainable fuel and chemical synthesis

Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century’s grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands