The interaction of the external donor (propyltrimethoxysilane - PTMS) with titanium-magnesium catalysts (TMCs) containing dibutylphthalate (DBP) as internal donor, which were prepared in different ways, was studied by chemical analysis and infrared diffuse reflectance spectroscopy (DRIFTS). The chemical composition of the catalysts after their interaction with heptane solutions of PTMS, PTMS/Al...

An egg-shell Pd/Al2O3 catalyst showed higher activity than a regular Pd/Al2O3 catalyst in the partial oxidation of methane to syngas, but a common problem of this reaction is the catalyst deactivation on stream. We attempted to modify the egg-shell catalyst via impregnation with some metal oxide additives. Although the addition of MgO did not show any beneficial effect, the addition of CaO and/...

using surface analysis, simultaneous effects of temperature (260-380ºc) and ethanol concentration (0-1%) on dimethyl ether (dme) selectivity, yields of hydrocarbon and dme, and methanol conversion were investigated in methanol dehydration reaction over γ-al2o3 catalyst. methanol conversion and yield of hydrocarbon/dme were found to be significantly affected by temperature and the temperature-et...

In industrial scale of Gas to Liquid (GTL) process in Fischer-Tropsch (FT) synthesis, a part of reactor outlet gases such as CO2 and CH4 as side reaction products, is usually recycled. In this study, the influence of CO2 and CH4 on the performance and selectivity of Co-Ru/Al2O3 catalyst is investigated by injection of these gases (0-20 vol. % of feed) to the feed stream. The effect of temperatu...

The relative contents of Cu+ and Cu2+ in solutions of anhydrous Nieuwland catalyst and CuCl2-added anhydrous Nieuwland catalyst were detected by X-ray photoelectron spectroscopy (XPS). Results indicated that Cu+ could be transformed into Cu2+ during the process of acetylene dimerization into monovinylacetylene, leading to deactivation of the catalyst. Moreover, the addition of Cu2+ inhibited th...

Deactivation kinetics of a V/Ti-oxide catalyst was studied in partial oxidation of toluene to benzaldehyde (BA) and benzoic acid (BAc) at 523–573 K. The catalyst consisted of 0.37 monolayer of VOx species and after oxidative pre-treatment contained isolated monomeric and polymeric metavanadate-like vanadia species under dehydrated conditions as was shown by FT Raman spectroscopy. Under the reac...

Niobium oxide as the promoter was doped in the V/WTi catalyst for the selective catalytic reduction (SCR) of NO. The results showed that the addition of Nb2O5 could improve the SCR activity at low temperatures and the 6wt.% additive was an appropriate dosage. The enhanced reaction activity of adsorbed ammonia species and the improved dispersion of vanadium oxide might be the reasons for the ele...

The formation of carbonaceous deposits (coke) in zeolite pores during catalysis leads to temporary deactivation of catalyst, necessitating regeneration steps, affecting throughput, and resulting in partial permanent loss of catalytic efficiency. Yet, even to date, the coke molecule distribution is quite challenging to study with high spatial resolution from surface to bulk of the catalyst parti...

Fluid catalytic cracking (FCC) is the main conversion process used in oil refineries. An X-ray microscopy method is used to show that metal poisoning and related structural changes in the zeolite active material lead to a non-uniform core–shell deactivation of FCC catalyst particles. The study links the detrimental effect of V and Ni poisoning with zeolite destruction and dealumination in a spa...