Fischer-Tropsch Synthesis on Multicomponent Catalysts: What Can We Learn from Computer Simulations?

Abstract

Abstract:In this concise review paper, we will address recent studies based on the generalized-gradient approximation (GGA) of the density functional theory (DFT) and on the periodic slab approach devoted to the understanding of the Fischer-Tropsch synthesis process on transition metal catalysts. As it will be seen, this computational combination arises as a very adequate strategy for the study of the reaction mechanisms on transition metal surfaces under well-controlled conditions and allows separating the influence of different parameters, e.g., catalyst surface morphology and coverage, influence of co-adsorbates, among others, in the global catalytic processes. In fact, the computational studies can now compete with research employing modern experimental techniques since very efficient parallel computer codes and powerful computers enable the investigation of more realistic molecular systems in terms of size and composition and to explore the complexity of the potential energy surfaces connecting reactants, to intermediates, to products of reaction. In the case of the Fischer-Tropsch process, the calculations were used to complement experimental work and to clarify the reaction mechanisms on different catalyst models, as well as the influence of additional components and co-adsorbate species in catalyst activity and selectivity.

Carbon Capture and Usage by MXenes

“…For CCS, materials are sought able to anchor CO 2 under standard conditions, a task challenged by the CO 2 high molecular stability and consequent low activity. More appealing than CCS are carbon capture and utilization (CCU) technologies, − aimed at using CO 2 as a C 1 chemical feedstock; by this, CO 2 can be chemically converted into other greener and potentially industrially useful chemicals, such as methanol, currently used in fuel cells, or carbon monoxide (CO), which can be later used in the Fischer–Tropsch process, synthesizing C n hydrocarbons. , The back-formation of re-usable fuels by CCU while using renewable sources of energy, and other sustainable reagents, for example, hydrogen (H 2 ) from water photocatalysis, conforms a plausible path toward closing the C-cycle.…”

Mechanistic Study of Carbon Monoxide Methanation over Pure and Rhodium- or Ruthenium-Doped Nickel Catalysts

“…Many different catalysts can be used for the catalysis of the above reactions, but the most common are based on Co, Fe, Rh, Ru, and Ni metals or alloys of these metals. − The main aim of the process is to produce a synthetic petroleum derivative, typically from coal, natural gas, or biomass to be used as synthetic lubrication oil or as synthetic fuel. Furthermore, the F-T synthesis involves a variety of competing chemical reactions which lead to a series of desirable products and undesirable byproducts. ,,− Process conditions and catalyst composition are usually chosen to favor higher-order reactions ( n > 1 in eq ) and thus minimize methane formation. − Most of the alkanes produced tend to be straight-chained, i.e., apt to be used as synthetic fuel, though some branched alkanes are also formed. Apart from alkanes production, competing reactions yield also alkenes, alcohols, and other oxygenated hydrocarbons. , Usually, only relatively small quantities of these nonalkane products are formed, although catalysts favoring some of these byproducts have been developed as well. , …”

Effect of CO Concentration on the α-Value of Plasma-Synthesized Co/C Catalyst in Fischer-Tropsch Synthesis

“…For example, precious metals like Au [23], and Pt [24], or in some cases, Ru have been employed to create multi-component catalysts such as (Ru + Co + Mn/Zr/SiO 2 ) to enhance Co reducibility [25]. This alters catalyst activity and selectivity or the catalyst's preference for a specific reaction mechanism [26], although some elements acting as promoters have been observed to aggravate metal particle sintering of the metal nanoparticles [27]. Other complex catalyst formulations such as carbon-supported cobalt manganese oxide (CoMnO x ) catalysts [28], are currently being developed.…”