Effect of alkali promotion on the catalytic performance of the synergetic K/Fe3O4-Fe5C2/Al2O3 catalyst for CO2 hydrogenation to light paraffins and olefines

Effect of alkali promoters (Li, Na, K) on the performance of Ru/Al2O3 catalysts for CO2 capture and hydrogenation to methane

The effect of alkali promotion on CO hydrogenation over [formula omitted

The effects of Cs promotion on [formula omitted] catalysts

Effects of alkali promoters on tri-metallic Co-Ni-Cu-based perovskite catalyst for higher alcohol synthesis from syngas

The present investigation deals with an alkali metal assisted synthesis of cobalt carbide (Co2C), starting from carburizing reduced complex precursors (obtained from Co3O4 with the addition of Li2O, Na2O and K2O) using CO as a carburization source. It is found that the Co2C formation could be significantly accelerated by the Li component. A comparative study reveals that the promotion effect of Li component may be related to the H2 adsorption on the reduced precursor, which enhanced the ability of the precursor to react with CO. Furthermore, the Co2C prepared from the precursor containing Li component shows a considerable increase in activity for CO hydrogenation and an improved fraction of higher alcohols in the total alcohol products, compared to the Co2C prepared without promoters. An attempt is made to elucidate the catalytic behavior of the as-prepared Co2C samples.

ABSTRACTMesoporous Fe2O3–Al2O3–CuO catalysts promoted with alkali oxides were synthesized and used in water gas shift reaction (WGSR) at high temperatures for hydrogen purification. These chromium-free catalysts were characterized using nitrogen adsorption/desorption, hydrogen temperature programmed reduction, X-ray diffraction (XRD), and transmission electron microscopy techniques. The synthesized catalysts with narrow single-modal pore size distribution in mesopore region possessed high specific surface area. The catalytic results revealed that except Cs, the addition of other alkali promoters declined the catalytic activity. However, all catalysts showed higher catalytic performance than the conventional commercial catalyst. The results showed an optimum content of Cs promoter (3 wt.%) for the promoted Fe–Al–Cu catalyst (3 wt.% Cs-FAC), which exhibited the highest activity in WGSR at high temperature.

Promoter effect of alkalis on CuO/CeO2/carbon nanotubes systems for the PROx reaction

13C NMR studies of CO adsorbed on supported rhodium catalysts: Effects of alkali promotion

Effect of the promoter presence in catalysts on the compositions of Fischer–Tropsch synthesis products

Plasma-activation of N2 via vibrational excitations or electronic excitations enhances the dissociative sticking probability on Ru-surfaces with respect to ground-state N2. We propose that this is primarily due to a weaker nitrogen–nitrogen bond, facilitating direct adsorption of both nitrogen atoms on the metallic surface, a pathway with a high barrier for ground-state N2 due to the short bond distance of 110 pm. Furthermore, we show that the increased sticking probability is not only a heating artefact, as the activation barrier for N2 dissociation decreases upon plasma-activation. Recent modelling studies show that the binding strengths of surface adsorbates, as well as the barrier for dissociation may change as a result of high electric fields, as well as high degrees of charging metal particles. We show that the effect of plasma-induced electric fields is negligible in dielectric barrier discharge reactors, and other non-thermal plasma reactors. The effect of alkali promoters on the local electric fields is orders of magnitude larger than the electric field of the plasma. The role of plasma-induced metal surface charging during N2 dissociation is currently not known for metal clusters on a support.

There has been much discussion based on indirect evidence about the site heterogeneity of catalysts for ammonia as well as the effect of alkali promotion. This paper presents the results from direct measurements using steady-state isotopic transient kinetic analysis (SSITKA) of surface site heterogeneity on Ru/SiO2 induced by K promotion. This heterogeneity is caused by the creation of a set of super active sites. It is the high activity of these sites, more than just the increase in number of surface intermediates, which produces the high activity of K promoted Ru for ammonia synthesis.

Strong electronic promotion of Co3O4 towards N2O decomposition by surface alkali dopants

Role of alkali promoters in K/MoS 2 catalysts for CO-H 2 reactions

The catalytic oxidalive coupling of metnane to ethylene and ethane with manganese oxide catalysts promoted with alkali metal and alkali metallic-chloride has been studied at atmospheric pressure in a fixed bed flow reactor.

The effect of alkali metals on the synthesis of methanethiol from CO/H2/H2S mixtures on the SBA-15 supported Mo-based catalysts