Long-Chain Terminal Alcohols through Catalytic CO Hydrogenation

Journal of Catalysis, 1987

A series of copper catalysts, promoted with 0.5% K2C03, was prepared and tested for thermal stability by measuring the surface area after successive 20-h treatments in flowing hydrogen at 250, 275, 300, and 325°C. Four of these catalysts and a commercial CuO/ZnO/A120, catalyst were tested for activity and selectivity in the synthesis of higher alcohols from a lH* t 2C0 synthesis gas at 10.5 MPa and 285 to 325°C. Two of these catalysts, CuO/ZnO/Cr203 and CuO/ZnO/Th02, had about the same initial activity as the commercial preparation. Catalysts which did not contain ZnO, namely, CuOIIIOz and CuO/ThO,, were relatively inactive. The CuO/ZnO/Th02 and commercial catalysts lost activity and surface area at 325"C, while the activity and surface area of the CuO/ ZnO/Cr,O, catalyst remained constant during 60 h onstream at the same temperature. The major alcohol products were methanol, 2-methyl-1-propanol, ethanol, and n-propanol and the selectivity to higher alcohols increased with increasing temperature. The Cd alcohol selectivities of the catalysts containing ThO? at 325°C were significantly larger than those of the other catalysts. The similar selectivities of these catalysts despite the marked difference in their activities suggests that ThO, promotes the production of higher alcohols. Q 1987 Academic press, hc.

Topics in Catalysis, 1995

Cu/ZnO/A1203 catalysts modified by compounds of manganese or cerium were prepared by coprecipitation or by impregnation and were tested for the synthesis of alcohol mixtures from synthesis gas at pressures of up to 70 bar. They were also examined by XPS both before and after the reaction. With both the impregnated and the coprecipitated catalysts, manganese increased the selectivity to higher alcohols (mainly isobutanol). However, in the case of cerium, the location of the cerium ions appeared to determine the selectivity; it shifted towards alkanes and CO2 when cerium was present at the surface of the catalyst (probably as CeO2), but to isobutanol when the cerium ions were present in the bulk. Changes were found in the selectivities of the catalyst doped with cerium with time on stream and these could be explained by a segregation of the cerium ions to the surface. Some of the mechanistic steps in the formation of higher alcohols as proposed in the literature were confirmed.

Journal of Molecular Catalysis, 1981

Polynuclear rhodium carbonyl complexes are present during the rhodium catalyzed conversion of carbon monoxide and hydrogen to alcohols. High pressure f.t.-i.r. analyses of reaction solutions containing [Rh17(CO)32-(S)2]3− suggest a catalyst manifold composed, almost exclusively, of that cluster. A related complex, [Rh17(CO)32−n(S)2(CHO)n](3 + n)−, has been prepared.The reactions of LiBH(C2H5)3 and LiBD(C2H5)3 with Os3(CO)12, Ru3-(CO)12, Ir4(CO)12, and Rh4(CO)12 have been studied by i.r., 1H and 2H n.m.r. and 13C n.m.r. With the exception of the rhodium containing system, results suggest the formation of formaldehyde and methanol in these reactions, as well as the existence of previously unreported polynuclear transition metal formyl complexes.Formyl complexes have been implicated as key intermediates in the manganese or cobalt catalyzed conversion of carbon monoxide and hydrogen to methanol. Mass spectral studies suggest that the reaction of acetic [13C] formic anhydride with sodium pentacarbonylmanganate, to give 13CO substituted pentacarbonylmanganese hydride, proceeds via formation of a short-lived neutral formyl complex, (CO)5Mn−13CHO.

Angewandte Chemie, 2014

Combining quantum‐mechanical simulations and synthesis tools allows the design of highly efficient CuCo/MoOx catalysts for the selective conversion of synthesis gas (CO+H2) into ethanol and higher alcohols, which are of eminent interest for the production of platform chemicals from non‐petroleum feedstocks. Density functional theory calculations coupled to microkinetic models identify mixed Cu–Co alloy sites, at Co‐enriched surfaces, as ideal for the selective production of long‐chain alcohols. Accordingly, a versatile synthesis route is developed based on metal nanoparticle exsolution from a molybdate precursor compound whose crystalline structure isomorphically accommodates Cu2+ and Co2+ cations in a wide range of compositions. As revealed by energy‐dispersive X‐ray nanospectroscopy and temperature‐resolved X‐ray diffraction, superior mixing of Cu and Co species promotes formation of CuCo alloy nanocrystals after activation, leading to two orders of magnitude higher yield to high ...

Journal of Natural Gas Chemistry, 2011

HNO 3-pretreated CNTs were employed as supports, and a special ultrasound-assisted impregnation method was designed to prepare supported Cu-Co catalysts for higher-alcohol synthesis from syngas. The catalysts used in this work were characterized by N 2 adsorption-desorption, TEM, XRD, H 2-TPR, CO-TPD techniques. It was found that the pre-treatment procedure of CNTs remarkably promoted the catalytic properties of the Cu-Co/CNTs catalysts. For the Cu-Co catalyst supported on CNTs pre-treated by 68 wt% HNO 3 , some active components were introduced into the CNTs channels, their dispersions and the amount of strongly adsorbed CO-species were improved. The CO conversion and alcohol yield on the HNO 3-pretreated Cu-Co/CNTs catalyst were increased by ∼21% and ∼69%, respectively, compared with those on the normal Cu-Co/CNTs catalyst.

Silica-supported copper/cobalt catalysts have been prepared in such a way as to generate bi-metallic copper/cobalt particles. The existence of alloy particles has been demonstrated by measuring the variation in the activity for the hydrogenolysis of propane, by temperature-programmed reduction, and by high-resolution analytical electron microscopy. When the catalysts were tested in a CO/Cop/H2 mixture at high pressure it was found that the bimetallic particles had very little activity for the synthesis of oxygenates. The only catalyst which produced a significant amount of higher oxygenates was a pure cobalt on silica catalyst which contained some unreduced cobalt ions. Although in the IFP (Institut Francais du P&role) catalysts, copper is believed to be a key component, it appears from our work that bimetallic particles of copper and cobalt are not necessary for the synthesis of higher alcohols. It seems that the key components of a higher alcohol synthesis catalyst are metallic cobalt and unreduced cobalt ions. Some possible roles for copper in such catalysts are discussed.

Journal of Catalysis, 2012

Co/CuZnO is known as a base metal catalyst active for C 2+ oxygenate synthesis. This study probed the interactions of the different components of Co/CuZnO catalysts on CO hydrogenation using Fischer-Tropsch synthesis (250°C, H 2 /CO = 2) and SSITKA. Only combination of all three metal components produced a catalyst with relatively high C 2+ oxygenate selectivity, but with much lower activity compared to that for Co/Al 2 O 3 . In situ reaction characterizations, albeit at somewhat different conditions than alcohol synthesis, helped explain interaction of the components. SSITKA, under methanation conditions, indicated that the most striking feature for the combination of Co with ZnO and/or Cu was a much decreased amount of reaction intermediates. Ethane hydrogenolysis results suggested that the different components for these catalysts were in close contact and few or no large ensembles (n P 12) of Co atoms existed, confirming that ZnO and/or Cu covered/blocked a substantial number of active sites on Co for CO hydrogenation.

Catalysis Today, 2022

Cu/SiO2 catalysts prepared by a deposition-decomposition (DD) method using ammonium hydroxide are currently among the most promising catalysts for oxalates hydrogenation to ethylene glycol (EG). Here, a Cu/SiO2 catalyst prepared by the DD method was pre-reduced at a) 200-350 °C in 100% H2, and 2) 200°C in a 50% H2/N2 mixture. Then, it was tested at 200 °C, and 25 barg, while EG yields were optimized, with H2-GHSV and H2/DMO ratios in the ranges 1000-4000 h-1 and 30-200 mol/mol. The calcined catalyst presents an XRD amorphous Cu phyllosilicate phase. After pre-reduction in pure H2 at 200 to 250°C (Tred), the Cu metallic surface area increased from 6 to 12 m 2 /gcat and slightly decreased at 350°C. Simultaneously, the silanol's band, measured by DRIFT experiments, increased with Tred. The highest ethylene glycol yield (91 %) was achieved after pre-reduction at 200 °C in pure hydrogen, working with an H2-GHSV and H2/DMO of 1050 h-1 and 68 mol/mol, respectively. The catalyst was stable for more than 36 h after a 20 h induction period. Catalyst characterization results as a function of Tred confirm that mixed-valence copper nanoparticles favor the EG selective formation, while side reactions leading to ethanol and 1,2-butanediol are related to exposed acidic and basic sites due to decreased Cu/support interactions.

Journal of Experimental Nanoscience, 2011

Three catalyst samples 10 wt% CuO/-Al 2 O 3 (CuAl), 10 wt%CuO þ 10 wt% Cr 2 O 3 /-Al 2 O 3 (CuCrAl) and 10 wt%CuO þ 20 wt% CeO 2 /-Al 2 O 3 (CuCeAl) have been taken for the study. Physico-chemical characteristics of the catalysts were determined by the methods of BET adsorption, X-ray diffraction and temperature-programmed reduction. Due to a strong interaction of CuO with Al 2 O 3 , resulting in the formation of copper aluminate the catalytic activity of CuO/-Al 2 O 3 has been reduced. The bi-oxide catalyst CuCrAl was more active than CuAl, thanks to the formation of high catalytically active spinel CuCr 2 O 4. The fact of very high activity of the CuCeAl sample can be explained by the presence of the catalytically active form CuO-CeO 2-Al 2 O 3. The kinetics of CO oxidation reaction on the given catalysts was studied at the temperature range between 200 C and 270 C. The values of initial partial pressures of carbon monoxide (P o CO), oxygen (P o O2) and carbon dioxide (P o CO2) were varied in ranges (hPa): 10 Ä 45; 33 Ä 100 and 0 Ä 30, respectively. It has been found that on all the catalysts, the common kinetic equation for the reaction was as follows: r ¼ kP CO P 0:5 O2 ð1 þ k 2 P 0:5 O2 þ k 3 P CO2 Þ , where r is the reaction rate, k is the reaction constant, and k 2 and k 3 are the O 2 and CO 2 adsorption constants, respectively. In the case of CuAl and CuCrAl, k 3 ¼ 0, and since k 2 P 0:5 o2) 1, the equation should become r ¼ k.P CO .