CO hydrogenation to methanol on Cu–Ni catalysts: Theory and experiment

Abstract

a b s t r a c tWe present density functional theory (DFT) calculations for CO hydrogenation on different transition metal surfaces. Based on the calculations, trends are established over the different monometallic surfaces, and scaling relations of adsorbates and transition states that link their energies to only two descriptors, the carbon oxygen binding energies, are constructed. A micro-kinetic model of CO hydrogenation is developed and a volcano-shaped relation based on the two descriptors is obtained for methanol synthesis. A large number of bimetallic alloys with respect to the two descriptors are screened, and CuNi alloys of different surface composition are identified as potential candidates. These alloys, proposed by the theoretical predictions, are prepared using an incipient wetness impregnation method and tested in a highpressure fixed-bed reactor at 100 bar and 250-300°C. The activity based on surface area of the active material is comparable to that of the industrially used Cu/ZnO/Al 2 O 3 catalyst. We employ a range of characterization tools such as inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis, in situ X-ray diffraction (XRD) and in situ transmission electron microscope (TEM) to identify the structure of the catalysts.

Exploring surface science and restructuring in reactive atmospheres of colloidally prepared bimetallic CuNi and CuCo nanoparticles on SiO2in situ using ambient pressure X-ray photoelectron spectroscopy

“…CuNi has also recently been identified by theory and experiment to be an active and highly selective 20 catalyst for methanol synthesis from syngas. 3 Given the strong likelihood of nickel segregation in such catalysts under reducing conditions, their optimisation and development for use as practical catalysts would considerably benefit from an improved understanding of this behaviour. These are just two examples, but given the prevalence of bimetallic catalytic systems, increasing our knowledge of these 25 dramatic restructuring effects is undoubtedly important in understanding their surface chemistry and enabling the rational development of improved catalytic systems.…”

“…In this field many 35 bimetallic systems have been considered, 2 but also some very systematic theoretical efforts have been employed to consider all plausible combinations of bimetallic surfaces. 3 Another merit of bimetallics has been the possibility of lowering cost while maintaining performance through the use of a precious metal in combination with a more abundant, cheaper metal, the properties of the former still being 40 retained. An example of this is the suggested use of Pt skin -Ni core nanoparticles…”

CO and CO2 Hydrogenation to Methanol Calculated Using the BEEF-vdW Functional

“…hydrogenation under industrially relevant reaction conditions calculated with the RPBE [4,13] and BEEF-vdW functional, respectively. As reported earlier, results using the RPBE functional suggest that hydrogenation of CO to methanol proceeds most efficiently via HCO, H 2 CO and H 3 CO. [4,8,14] The highest free energy barrier in this sequence is the second hydrogenation step, HCO + H -> H 2 CO. Under the reaction conditions chosen here (see Figure caption 1 magnitude.…”

CatMAP: A Software Package for Descriptor-Based Microkinetic Mapping of Catalytic Trends

“…The combination of these techniques leads to the ability to predict trends in kinetic properties of heterogeneous catalysts across a range of surfaces using a ''descriptor-based'' analysis [10,11]. This technique has been applied to a large number of chemical and electrochemical reactions, and often results in the prediction of novel catalysts with experimentally verifiable activity [8,[23][24][25][26][27].…”