bimetal Nickel catalysts

近年来，双金属纳米颗粒成为科学研究的焦点，很大程度上是由于它们有趣的催化特性。对于许多经济上重要的工艺，第二种金属的合金化提供了优化活性、选择性和长期稳定性的可能性。在这种情况下，提出的项目的目的是测试合金成分和粒度的双参数优化的假设对Ni-Cu和Ni-Fe的催化活性和抗失活能力。选择一氧化碳甲烷化反应作为代表性试验反应，该反应在费托合成或氨合成上游等工艺过程中起着重要作用，保护铁催化剂不被CO失活。由于前期研究结果看好，选择了合金元素Fe和Cu。为了达到项目目标，有必要研究具有高度确定组成和粒度的Ni-Cu和Ni-Fe催化剂的初始活性和失活行为。为了研究催化剂的催化性能和失活行为，需要考虑许多影响因素。这些是合金成分，粒度，反应温度，反应时间，气相组成。所有三个指标，期望反应的催化活性，焦炭形成动力学和烧结行为，都在一定程度上取决于这些影响因素。因此，减少实验矩阵是必要的，以减少所需的实验次数。因此，根据前面的工作，催化反应的排出气体的气相组成将保持不变。催化剂的初始活性取决于镍基合金催化剂颗粒中铜和铁的浓度。粒度的影响将通过研究具有固定组成但粒度可变的颗粒来单独观察。这将通过在火花放电过程中操纵颗粒大小的可能性来实现，并且可以通过在气相状态下产生接近单分散颗粒的分类来进一步改进。随着反应时间的增加，催化活性的损失将分别研究两种主要机制，颗粒生长和焦化，这是由气溶胶过程实现的。再一次，参数组成和粒度将分别研究它们对机理的影响。

Bimetal nanoparticles have moved into the focus of science in recent years to a large part due to their interesting catalytic properties. For many economically important processes the alloying of a second metal offers the possibility to optimize activity, selectivity and long term stability.In this context, the aim of the proposed project is the testing of the hypothesis of a two-parameter optimum of alloy composition and particle size for the catalytic activity and deactivation resistance for Ni-Cu and Ni-Fe.Methanation of carbon monoxide was selected as representative test reaction, which plays an important role in a number of technical processes, such as Fischer-Tropsch- synthesis or upstream of ammonia-synthesis to protect the iron catalyst from deactivation by CO. As alloying elements Fe and Cu were selected, due to promising results in earlier studies. To reach the project goal the investigation of the initial activity and the deactivation behavior of Ni-Cu and Ni-Fe catalysts with highly defined composition and particle size are necessary. For the investigation of the catalytic properties and the deactivation behavior a number of factors of influence need to be taken into account. These are alloy composition, particle size, reaction temperature, reaction time, and gas phase composition. All three target figures, catalytic activity for the desired reaction, the kinetics of coke formation and sintering behavior, are expected to depend on these factors of influence to some extent. A reduction of the experimental matrix is therefore necessary to reduce the number of required experiment. Based on preceding work the gas phase composition of educt gases for the catalytic reaction will therefore be kept constant. The initial activity of the catalysts shall be characterized in dependence on the the Copper- and Iron-concentration in Nickel-based alloyed catalyst particles. The influence of particle size will be observed separately by investigating particles of a set composition but variable particle size. This will be accomplished by the possibility of manipulating the particle size in the spark discharge process and can further be improved by classification in the gasborne state yielding close to monodisperse particles. The loss of catalytic activity with increasing reaction time will be investigated separately for the two dominating mechanisms, particle growth and coking, which is enabled by aerosol processes. Again the parameters composition and particle size will be investigated separately in their influence on the mechanisms.