Promoting the Selectivity of Pt/m-ZrO2 Ethanol Steam Reforming Catalysts with K and Rb Dopants

The ethanol steam reforming reaction (ESR) was investigated on unpromoted and potassium- and rubidium-promoted monoclinic zirconia-supported platinum (Pt/m-ZrO2) catalysts. Evidence from in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization indicates that ethanol dissociates to ethoxy species, which undergo oxidative dehydrogenation to acetate followed by acetate decomposition. The acetate decomposition pathway depends on catalyst composition. The decarboxylation pathway tends to produce higher overall hydrogen selectivity and is the most favored route at high alkali loading (2.55 wt.% K and higher or 4.25 wt.% Rb and higher). On the other hand, decarbonylation is a significant route for the undoped catalyst or when a low alkali loading (e.g., 0.85% K or 0.93% Rb) is used, thus lowering the overall H2 selectivity of the process. Results of in situ DRIFTS and the temperature-programmed reaction of ESR show that alkali doping promotes forward acetate decomposition while exposed metallic sites tend to facilitate decarbonylation. In previous work, 1.8 wt.% Na was found to hinder decarbonylation completely. Due to the fact that 1.8 wt.% Na is atomically equivalent to 3.1 wt.% K and 6.7 wt.% Rb, the results show that less K (2.55% K) or Rb (4.25% Rb) is needed to suppress decarbonylation; that is, more basic cations are more efficient promoters for improving the overall hydrogen selectivity of the ESR process.

Steam Reforming of Chloroform-Ethyl Acetate Mixture to Syngas over Ni-Cu Based Catalysts

NiCuMoLaAl mixed oxide catalysts are prepared and applied in the steam reforming of chloroform-ethyl acetate (CHCl3-EA) mixture to syngas in the present work. The pre-introduction of Cl- ions using chloride salts as modifiers aims to improve the chlorine poisoning resistance. Catalytic tests show that KCl modification is obviously advantageous to increase the catalytic life. The destruction of catalyst structure induced by in situ produced HCl and carbon deposits that occurred on acidic sites are two key points for deactivation of reforming catalysts. The presence of Cl− ions gives rise to the formation of an Ni-Cu alloy, which exhibits a synergetic effect on catalyzing reforming along with metallic Ni crystals formed from excess nickel species, and giving an excellent catalytic stability. Less CHCl3 and more steam can also increase the catalytic stable time of KCl-modified NiCuMoLaAl reforming catalyst.

The effect of indium introduction method on the properties of Pt/In/Al2O3-Cl reforming catalyst

The effect of 0.3 wt.% indium, which was introduced at the steps of alumina peptization or impregnation, on the properties of platinumalumina reforming catalysts was studied. Doping with indium at the impregnation step produced a smaller decrease in the total acidity of the support and hence in the heptane conversion for the corresponding Pt/In/Al2O3-Cl catalyst. The most pronounced decrease in selectivity of hydrogenolysis and hydrocracking and the maximum i-C5-7 : toluene selectivity ratio were observed for this sample as compared to the undoped catalysts with indium introduction at the peptization step.

The sol-gel autocombustion as a route towards highly CO2-selective, active and long-term stable Cu/ZrO2 methanol steam reforming catalysts

The adaption of the sol-gel autocombustion method to the Cu/ZrO2 system opens new pathways for the specific optimisation of the activity, long-term stability and CO2 selectivity of methanol steam reforming...

PET waste as organic linker source for the sustainable preparation of MOF-derived methane dry reforming catalysts

An active and stable catalyst for dry reforming of methane composed of Ni0 nanoparticles highly dispersed on a lamellar alumina was prepared by employing a sacrificial metal–organic framework derived from PET wastes.

Comparison of novel Ni doped exsolution perovskites as methane dry reforming catalysts

Three perovskite-type materials with a different amount of B-site Ni doping have been tested for their catalytic performance during me-thane dry reforming (MDR) followed by characterization with X-ray dif-fraction (XRD) and scanning electron microscopy (SEM). They could be activated via a reductive treatment (either during a pre-reduction step or di-rectly in reducing reaction atmosphere), the main activating mechanism be-ing the formation of Ni nanoparticles on the surface by exsolution. The catalytic activity increased with the particle size and density. The particle distribution properties could be improved by increasing the amount of Ni doping from 3 % to 10 %, by using an A-site sub-stoichiometric perovskite and by choosing a higher annealing temperature during material prepara-tion. A deactivation over time was observed, due to segregation of CaCO3 on the surface, but no coking or particle sintering occurred