Catalytic Performance of Ni/CeO2/X-ZrO2 (X = Ca, Y) Catalysts in the Aqueous-Phase Reforming of Methanol

In this study, we reported on the effect of promoting Ni/ZrO2 catalysts with Ce, Ca (two different loadings), and Y for the aqueous-phase reforming (APR) of methanol. We mainly focused on the effect of the redox properties of ceria and the basicity provided by calcium or yttrium on the activity and selectivity of Ni in this reaction. A systematic characterization of the catalysts was performed using complementary methods such as XRD, XPS, TPR, CO2-TPD, H2 chemisorption, HAADF-STEM, and EDS-STEM. Our results reveal that the improvement in reducibility derived from the incorporation of Ce did not have a positive impact on catalytic behaviour thus contrasting with the results reported in the literature for other Ce-based catalytic compositions. On the contrary, the available Ni-metallic surface and the presence of weak basic sites derived from Ca incorporation seem to play a major role on the catalytic performance for APR of methanol. The best performance was found for a Ce-free catalyst with a molar Ca content of 4%.

Fischer-Tropsch Synthesis: Cd, In and Sn Effects on a 15%Co/Al2O3 Catalyst

The effects of 1% of Cd, In and Sn additives on the physicochemical properties and Fischer-Tropsch synthesis (FTS) performance of a 15% Co/Al2O3 catalyst were investigated. The fresh and spent catalysts were characterized by BET, temperature programmed reduction (TPR), H2-chemisorption, NH3 temperature programmed desorption (TPD), X-ray absorption near edge spectroscopy (XANES), and X ray diffraction (XRD). The catalysts were tested in a 1 L continuously stirred tank reactor (CSTR) at 220 °C, 2.2 MPa, H2/CO = 2.1 and 20–55% CO conversion. Addition of 1% of Cd or In enhanced the reduction degree of 15%Co/Al2O3 by ~20%, while addition of 1% Sn slightly hindered it. All three additives adversely impacted Co dispersion by 22–32% by increasing apparent Co cluster size based on the H2-chemisorption measurements. However, the decreased Co active site density resulting from the additives did not result in a corresponding activity loss; instead, the additives decreased the activity of the Co catalysts to a much greater extent than expected, i.e., 82–93%. The additional detrimental effect on catalyst activity likely indicates that the Cd, In and Sn additives migrated to and covered active sites during reaction and/or provided an electronic effect. XANES results showed that oxides of the additives were present during the reaction, but that a fraction of metal was also likely present based on the TPR and reaction testing results. This is in contrast to typical promoters that become metallic at or below ~350 °C, such as noble metal promoters (e.g., Pt, Ru) and Group 11 promoters (e.g., Ag, Au) on Co catalysts in earlier studies. In the current work, all three additives remarkably increased CH4 and CO2 selectivities and decreased C5+ selectivity, with the Sn and In additives having a greater effect. Interestingly, the Cd, In, or Sn additives were found to influence hydrogenation and isomerization activities. At a similar conversion level (i.e., in the range of 40–50%), the additives significantly increased 2-C4 olefin content from 3.8 to 10.6% and n-C4 paraffin from 50 to 61% accompanied by decreases in 1-C4 olefin content from 48 to 30%. The Sn contributed the greatest impact on the secondary reactions of 1-olefins, followed by the In and Cd. NH3-TPD results suggest enhanced acid sites on cobalt catalysts resulting from the additives, which likely explains the change in selectivities for the different catalysts.

Ortho-chloronitrobenzene hydrogenation over carbon supported Rh-Cu catalysts

The promotional effect of Cu on the catalytic performance of supported Rh catalysts in the selective hydrogenation of ortho-chloronitrobenzene to ortho-chloroaniline was studied using carbon support. The catalysts were characterised by BET, H2 chemisorption, TEM. Rh surface is partially covered by Cu as a result of interaction between Rh and Cu. The superficial Cu species activate the N=O bond of chloronitrobenzene. Thus, the bimetallic RhCu catalysts exhibited excellent performance, producing chloroaniline with excellent selectivity.

Effects of Lanthanum on the Structure and the Catalytic Performance of Ni/Al2O3 Catalysts for the Hydrotreating of Crude 2-Ethylhexanol

To study the effects of La modifier on Ni/γ-Al2O3 catalysts for the hydrotreating of crude 2-ethylhexanol, four samples with various La contents were prepared by the hydrothermal deposition method and characterized by ICP–AES, XRD, XPS, TPR, and H2 chemisorption. It was found that the number of catalytic active sites of the four samples with a similar Ni loading follows the order: Ni/La0/Al (13.2μmol gcat-1) < Ni/La0.5/Al (15.1μmol gcat-1) < Ni/La2.0/Al (15.8μmol gcat-1) < Ni/La1.0/Al (17.1μmol gcat-1). The results indicate that the catalyst modified by an appropriate La can obtain more active centers and higher hydrogenation performance because it possesses a higher surface Ni content and an appropriate Ni dispersion degree.