Hydroformylation of olefins by Au/Co3O4 catalysts

The hydroformylation of olefins over supported gold catalysts in an autoclave reactor under mild conditions (100–140 °C, 3–5 MPa) has been studied. Over Au/AC (activated carbon), Au/PVP (polyvinylpyrrolidone), Au/Al₂O₃, Au/TiO₂, Au/Fe₂O₃, Au/ZnO, Au/CeO₂ and Co₃O₄, 1-olefin mainly remained unchanged and the major products were isomerized olefins or hydrogenated paraffin. In contrast, Au nanoparticles deposited on Co₃O₄ led to remarkably high catalytic activities in hydroformylation reaction with selectivities above 85% to desired aldehydes. The hydroformylation of olefins proceeds preferentially at temperatures below 140 °C, above which the reactions of olefins gradually shifted to isomerization and then to hydrogenation. It appeared that the activity and selectivity of hydroformylation reaction strongly depend on the molecular structure of olefins, which could be ascribed to steric constraints as internal olefins are relatively inappropriate to form alkyl group and subsequent acyl group by insertion of CO. The Au/Co₃O₄ catalyst can be recycled by simple decantation with slight decrease in catalytic activity along with an increase in recycle times, which is a great advantage over homogeneous catalysts. The role of gold nanoparticles can be assumed to dissociate hydrogen molecule into atomic species which reduce Co₃O₄ to Co metal under mild reaction conditions.     

Selective Hydrogenation of <Emphasis Type="Italic">trans</Emphasis>-Cinnamaldehyde over SiO<Subscript>2</Subscript>-Supported Co–Ir Bimetallic Catalysts

Selective hydrogenation of trans-cinnamaldehyde was studied on SiO₂-supported Co–Ir bimetallic catalysts. Addition of Ir to Co/SiO₂ increased the hydrogenation selectivity and activity of cinnamaldehyde to the corresponding cinnamyl alcohol (UOL). A selectivity as higher as 93% to UOL at ambient temperature under H₂ pressure of 2.0 MPa was obtained over catalyst with loadings of 10 wt% Co and 0.5 wt% Ir (Co_10.0Ir_0.5/SiO₂). The XRD, Raman and TPR results showed that the higher dispersed Co₃O₄ particles were formed on SiO₂ due to the addition of Ir, which increased the reducibility of Co₃O₄ to Co⁰. The reduction of oxidized Co–Ir/SiO₂ samples occurred at the temperatures with about 200 K lower than that of the one without Ir species as evidenced by the observations of TPR and in-situ Raman characterizations. The XPS results indicated that the large parts of Co₃O₄ in the sample of Co–Ir/SiO₂ were reduced to Co⁰, but only small parts of that were reduced to Co⁰ in the sample of Co/SiO₂ under flowing 5%H₂/Ar at 673 K. The CO chemisorptions revealed that the irreversible uptakes of CO on the reduced Co–Ir/SiO₂ sample was much higher than those on the reduced Co/SiO₂ and Ir/SiO₂, and also higher than the combination of that on the reduced Co/SiO₂ and Ir/SiO₂, respectively. The experimental data suggested that the presence of Ir played a key role in the reduction of Co₃O₄ to Co⁰ through a strong interaction between them and that the amount of Co⁰ at the catalyst surfaces was correlated to the activity and more importantly to the UOL selectivity.     

Synergy of ruthenium and cobalt in SiO2-supported catalysts on ethylene hydroformylation

Dynamic hydroformylation of ethylene at atmospheric pressure and 150°C has been studied in a fixed bed reactor over ruthenium- and cobalt-containing SiO₂-supported catalysts (1% Ru loading). Any combination of ruthenium and cobalt precursors leads to significant improvement of hydroformylation activity with respect to those of monometallic catalysts. The optimal atomic ratio of Co:Ru is estimated to be 3:1 for ideal catalytic activity. A catalyst derived from Ru₃(CO)₁₂ and Co₂(CO)₈ is most active. A catalyst derived from metal carbonyls is generally more active than a catalyst prepared from metal salts. Metal chlorides retard the preparation of active catalysts in most cases. The catalysts studied exhibit fairly good catalytic stability. The determined rate enhancement of ethylene hydroformylation suggests a synergy of ruthenium and cobalt, which is understood as catalysis by bimetallic particles or ruthenium and cobalt monometallic particles in intimate contact. The synergy causes high ethylene hydrogenation activity while giving enhanced ethylene hydroformylation activity. Meanwhile, the potential of the ruthenium-based catalysts is evaluated from both catalytic performances and cost by comparison with the corresponding rhodium-based ones.     

A new supported Fe-MnO catalyst for the production of light olefins from syngas. II. Effect of support on the secondary reactions of C2H4

The TPSR technique was used to investigate the effect of the support on the secondary reactions of ethylene formed during CO hydrogenation. Based on the results of CO hydrogenation and CO/H₂-TPSR characterization, it was found that different supports induced different secondary reactions, and thus affected the selectivity to light olefins directly. The Fe-MnO/MgO catalyst (based on basic support) causes disproportionation of C₂H₄, and thus, leads to the formation of C₃H₆. The Fe-MnO/Al₂O₃ catalyst (based on acidic support) showed obvious hydrogenation of C₃H₆. The disproportionation of C₂H₄ was also promoted by the Fe-MnO/Al₂O₃ catalyst, but because of its activity for C₃H₆ hydrogenation, a large amount of C₃H₈ was produced. The different C₂H₄ secondary reactions are relevant to different CO/H₂ reaction pathways over the catalyst surface, so the Fe-MnO/MgO catalyst is a desirable catalyst for the production of light olefins from CO/H₂ while the Fe-MnO / Al₂O₃ catalyst was not so.     

Binary spinel cobaltites of nickel,copper and zinc as precursors of catalysts for carbon oxides methanation

The hydrogenation of carbon oxides (CO and CO₂) on bimetallic Cu/Co and Ni/Co as well as Co/ZnO catalysts obtained by reduction of the corresponding spinel cobaltites Me_xCo_3-xO₄ is investigated. The predominant hydrogenation process is methanation and in the case of nickel cobaltite high and stable activity and selectivity are reached, no carbon deposition and carbide formation being observed.     

Selective production of methanol from syngas over LaTi1−xCuxO3 mixed oxides

Carbon monoxide hydrogenation was studied over partially substituted copper-containing LaTi_1–xCu_xO₃ oxides and on copper supported on La₂O₃. The unsubstituted (x = 0) oxide was weakly active for CO hydrogenation, whereas all the other oxides were more active and exhibited high selectivity to methanol. Particularly, for substitutions x = 0.5–0.6, where the perovskite structure was observed, CO conversions close to 22% and selectivity close to 80% were found. Cu/La₂O₃ was, however, less active and yielded CO₂ and hydrocarbons as the major products. Using X-ray photoelectron spectroscopy it was determined that under reaction conditions copper exists as reduced species. The L₃VV X-ray induced Auger transition at 1849.2 eV observed for a representative LaMn_0.5Cu_0.5O₃ catalyst prereduced and used in CO hydrogenation at 573 K, suggests that Cu⁺ species dominates in spent catalyst. These Cu⁺ species are believed to be stable under reaction conditions in the perovskite structure, only a slight Cu enrichment occurs on the topmost layer of catalysts.     

A highly active bimetallic supported Rh–Co hydroformylation catalyst prepared from RhCl3 and Co2(CO)8

The preparation of a highly active bimetallic SiO₂‐supported Rh–Co catalyst from RhCl₃ and Co₂(CO)₈ (Rh:Co= 1 : 3 atomic ratio) has been studied by IR spectroscopy and ethylene hydroformylation, etc. Two steps are involved in the preparative process: (1) surface‐mediated synthesis of Rh⁺(CO)₂/SiO₂ from calcined RhCl₃/SiO₂; (2) impregnation of Rh⁺(CO)₂/SiO₂ with a Co₂(CO)₈ solution followed by H₂ reduction at 623 K. The IR results of reductive carbonylation of calcined RhCl₃/SiO₂ have been compared to those of uncalcined RhCl₃/SiO₂ at 373 K. In situ IR observations, extraction results and elemental analysis suggest that approximately 50% of RhCl₃ are transformed to Rh₂O₃ on the SiO₂ surface and that calcined RhCl₃/SiO₂ is converted to a mixture of [Rh(CO)₂Cl]₂ and [Rh(CO)₂O₂ (O_s: surface oxygen) under CO at 373 K. When this SiO₂‐supported mixture was submitted to impregnation with a Co₂(CO)₈ solution at room temperature, IR study and elemental analysis show that [Rh(CO)₂Cl]₂ reacts easily with Co₂(CO)₈ on the surface to give RhCo₃(CO)₁₂, whereas [Rh(CO)₂O₂ does not react with Co₂(CO)₈. Catalytic study in steady‐state ethylene hydroformylation shows that a catalyst thus derived is more active than a catalyst derived from RhCo₃(CO)₁₂/SiO₂ and a catalyst derived by coimpregnation of [Rh(CO)₂Cl]₂ and Co₂(CO)₈ on SiO₂. This result suggests that the high rhodium dispersion of [Rh(CO)₂O₂ plays a crucial role in the formation of highly dispersed bimetallic Rh–Co sites. This revised version was published online in July 2006 with corrections to the Cover Date.     

Liquid phase hydrogenation of benzene to cyclohexene on ruthenium catalysts supported on zinc oxide‐based binary oxides

A series of binary oxide‐supported ruthenium catalysts with zinc oxide as a component of the support was prepared. Zinc oxide was a major component of the support, the other component was lanthanum oxide, zirconium oxide, chromium oxide, barium oxide, gallium oxide, strontium oxide, calcium oxide or magnesium oxide. Liquid phase hydrogenation of benzene to cyclohexene was studied on these catalysts in a stirred tank reactor at a hydrogen pressure of 2.5–6.0 MPa and 448 K. The reaction was operated in a kinetic‐controlled regime. In order to have high selectivity to cyclohexene, a large amount of water should be present. In addition, the reaction medium should be an alkaline solution. The yield of cyclohexene was in the order: Ru/Ga₂O₃–ZnO > Ru/La₂O₃–ZnO > Ru/Cr₂O₃–ZnO > Ru/ZrO₂–ZnO > Ru/MgO–ZnO = Ru/CaO–ZnO = Ru/SrO–ZnO = Ru/BaO–ZnO.Ru/Ga₂O₃–ZnO demonstrated the highest selectivity and yield of cyclohexene. A model of the low solubilities of reactants in the water film surrounding the catalyst can explain the reaction behavior of the catalyst. © 2001 Society of Chemical Industry     

Characterization of Fischer–Tropsch Cobalt-Based Catalytic Systems (Co/SiO<Subscript>2</Subscript> and Co/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>) by X-ray Diffraction and Magnetic Measurements

Results of the characterization of six Co-based Fischer–Tropsch (FT) catalysts, with 15% Co loading and supported on SiO₂ and Al₂O₃, are presented. Room temperature X-ray diffraction (XRD), temperature and magnetic field (H) variation of the magnetization (M), and low-temperature (5 K) electron magnetic resonance (EMR) are used for determining the electronic states (Co⁰, CoO, Co₃O₄, Co²⁺) of cobalt. Performance of these catalysts for FT synthesis is tested at reaction temperature of 240 °C and pressure of 20 bars. Under these conditions, 15% Co/SiO₂ catalysts yield higher CO and syngas conversions with higher methane selectivity than 15% Co/Al₂O₃ catalysts. Conversely the Al₂O₃ supported catalysts gave much higher selectivity towards olefins than Co/SiO₂. These results yield the correlation that the presence of Co₃O₄ yield higher methane selectivity whereas the presence of Co²⁺ species yields lower methane selectivity but higher olefin selectivity. The activities and selectivities are found to be stable for 55 h on-stream.     

Study on catalysis by carbonyl cluster-derived SiO2-supported rhodium for ethylene hydroformylation

Atmospheric hydroformylation of ethylene was studied under differential conditions over Rh₄(CO)₁₂-derived Rh/SiO₂ catalysts. The specific activities as functions of Rh dispersions show that ethylene hydroformylation is structure sensitive and ethylene hydrogenation structure insensitive. These structural dependences and in situ IR observations show that Rh⁰ is the unique active site for catalytic ethylene hydroformylation on Rh/SiO₂. The reactions of Rh⁰-coordinated CO and Rh⁰-adsorbed CO with C₂H₄ + H₂ at 293 K were monitored by IR spectroscopy. The linear CO adsorbed on Rh⁰/SiO₂ is consumed with formation of propanal, whereas the coordinated CO in Rh₆(CO)₁₆/SiO₂ and its derivative do not participate in CO insertion. IR study of the thermal decomposition of Rh₆(CO)₁₆/SiO₂ indicates that the cluster can be stabilized on the surface up to 548 K by gaseous CO under hydroformylation conditions. Moreover, the Rh₆(CO)₁₆/SiO₂ system exhibits increased catalytic hydroformylation activity with reducing coordinated CO. These results show that coordinative unsaturation on the Rh⁰ surface is necessary for heterogeneously rhodium-catalyzed hydroformylation and that totally decarbonylated Rh⁰/SiO₂ is most effective. In addition, the oxidation of Rh⁰ by surface OH^? is discussed.     

Ethanol Steam Reforming on Co/CeO2: The Effect of ZnO Promoter

A series of ZnO promoted Co/CeO₂ catalysts were synthesized and characterized using XRD, TEM, H₂-TPR, CO chemisorption, O₂-TPO, IR-Py, and CO₂-TPD. The effects of ZnO on the catalytic performances of Co/CeO₂ were studied in ethanol steam reforming. It was found that the addition of ZnO facilitated the oxidation of Co⁰ via enhanced oxygen mobility of the CeO₂ support which decreased the activity of Co/CeO₂ in C–C bond cleavage of ethanol. 3 wt% ZnO promoted Co/CeO₂ exhibited minimum CO and CH₄ selectivity and maximum CO₂ selectivity. This resulted from the combined effects of the following factors with increasing ZnO loading: (1) enhanced oxygen mobility of CeO₂ facilitated the oxidation of CH _x and CO to form CO₂; (2) increased ZnO coverage on CeO₂ surface reduced the interaction between CH _x /CO and Co/CeO₂; and (3) suppressed CO adsorption on Co⁰ reduced CO oxidation rate to form CO₂. In addition, the addition of ZnO also modified the surface acidity and basicity of CeO₂, which consequently affected the C₂–C₄ product distributions.     

Surface-grafted triruthenium ketenylidene clusters and their catalytic activity in co exchange and hydroformylation of ethylene

A triruthenium ketenylidene cluster [PPN]₂[Ru₃(CO)₉(CCO)] was deposited on MgO, SiO₂, and SiO₂-Al₂O₃, and the nature of surface species on the oxides were studied by an IR spectroscopic study along with catalytic performances in¹³CO exchange reaction and hydroformylation of ethylene. The IR study suggested the stoichiometric protonation of [Ru₃(CO)₉(CCO)]^2-with surface hydroxyl groups on SiO₂ and SiO₂-Al₂O₃ to give [HRu₃(CO)₉(CCO)]^– and H₂Ru₃(CO)₉(CCO), respectively. H₂Ru₃(CO)₉(CCO)/SiO_2– Al₂O₃ was active for¹³CO exchange reaction, while [Ru₃(CO)₉(CCO)]^2–/MgO showed high activity and selectivity toward propanol in hydroformylation of ethylene.     

The oxidative coupling of methane by sodium promoted lanthanide catalysts

The characteristics of La₂O₃ catalysts with three different supports (BaCO₃, MgO, and ZnO), two different alkaline metal promoters (Na₂O and Na₂CO₃), and a china clay have been investigated. The relationship of the surface basicity of the support to the activity and selectivity of the catalyst were studied by TPD. The results showed that the surface basicity of these three supports decreased in the following order: BaCO₃ > MgO > ZnO. The choice of Na₂O as a promoter in La₂O₃/(BaCO₃ or MgO) had a better effect than the choice of Na₂CO₃. The Na₂O promoter could increase not only the catalytic activity and the C₂ selectivity, but also lower the optimal reaction temperature. Addition of 15% clay into the La₂O₃–alkaline metal catalysts could increase the strength of the catalyst and lower the optimum reaction temperature.     

Methanol synthesis over Cu/SiO2 catalysts

The rates of CO and CO/CO₂ hydrogenation at 4.2 MPa and 523 K are reported for a series of Cu/SiO₂ catalysts containing 2 to 88 wt.% Cu. These catalysts were prepared on a variety of silica sources using several different Cu deposition techniques. In CO/CO₂ hydrogenation, the rate of methanol formation is proportional to the exposed Cu surface area of the reduced catalyst precursor, as determined by N₂O frontal chromatography. The observed rate, 4.2×10^–3 mole CH₃OH/Cu site-sec, is within a factor of three of the rates reported by others over Cu/ZnO and Cu/ZnO/Al₂O₃ catalysts under comparable conditions. These results suggest that the ZnO component is only a moderate promoter in methanol synthesis. Hydrogenation of CO over these catalysts also gives methanol with high selectivity, but the synthesis rate is not proportional to the Cu surface area. This implies that another type of site, either alone or in cooperation with Cu, is involved in the synthesis of methanol from CO.     

Surface Properties of CaO (or BaO)–La2O3–MgO Catalysts and Their Performance in Oxidative Coupling of Methane

CaO–La₂O₃–MgO and BaO–La₂O₃–MgO catalysts with different compositions have been studied for their bulk and surface properties (viz. crystal phases, surface area, acidity/acid strength distribution, basicity/base strength distribution, etc.) and catalytic activity/selectivity in the oxidative coupling of methane (OCM) at different processing conditions (reaction temperature, 700–850°C; CH₄/O₂ ratio in feed, 3·0, 4·0 and 8·0 and GHSV, 102000 and 204000 cm³ g⁻¹ h⁻¹). The surface acidity and strong basicity of La₂O₃–MgO are found to be increased due to the addition of a third component (CaO or BaO), depending upon its concentration in the catalyst. The addition of CaO or BaO to La₂O₃–MgO OCM catalyst causes a significant improvement in its performance. Both the CaO- and BaO-containing catalysts show a high activity and selectivity at 800°C, whereas, the activity and selectivity of BaO-containing catalysts at 700°C is lower than that of CaO-containing catalysts. © 1997 SCI.     

Perovskite-type oxide ACo0.8Bi0.2O2.87 (A=La0.8Ba0.2): a catalyst for low-temperature CO oxidation

Perovskite-type oxide ACo_0.8Bi_0.2O_2.87 (A=La_0.8Ba_0.2) has been investigated as a catalyst for the oxidation of carbon monoxide. X-ray diffraction results revealed that the catalyst is single-phase and cubic in structure. The results of chemical analysis indicated that in ACo_0.8Bi_0.2O_2.87, bismuth is pentavalent whereas cobalt is trivalent as well as bivalent; in La_0.8Ba_0.2CoO_2.94, cobalt ions exist as Co³⁺ and Co⁴⁺. The substitution of Bi for Co enhanced the catalytic activity of the perovskite-type oxide significantly. Over the Bi-incorporated catalyst, at equal space velocities and with the rise in CO/O₂ molar ratio, the temperature for 100% CO conversion shifted to a higher range; at a typical space velocity of 30000 h^–1 and a CO/O₂ molar ratio of 0.67/1.00, 100% CO conversion was observed at 250°C. Over ACo_0.8Bi_0.2O_2.87, at equal CO/O₂ molar ratio, the temperature for 100% CO conversion decreased with a drop in space velocity; the lowest being 190°C at a space velocity of 5000 h^–1. The result of O₂-TPD study illustrated that the presence of Bi ions caused the lattice oxygen of La_0.8Ba_0.2CoO_3– to desorb at a lower temperature. The results of TPR, ¹⁸O/¹⁶O isotopic exchange, and CO-pulsing investigations demonstrated that the lattice oxygen of the Bi-doped catalyst is highly mobile.     

Effect of component interaction on the activity of Co/CuZnO for CO hydrogenation

Co/CuZnO is known as a base metal catalyst active for C₂₊ oxygenate synthesis. This study probed the interactions of the different components of Co/CuZnO catalysts on CO hydrogenation using Fischer–Tropsch synthesis (250 °C, H₂/CO = 2) and SSITKA. Only combination of all three metal components produced a catalyst with relatively high C₂₊ oxygenate selectivity, but with much lower activity compared to that for Co/Al₂O₃. 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 ? 12) of Co atoms existed, confirming that ZnO and/or Cu covered/blocked a substantial number of active sites on Co for CO hydrogenation.     

On the development of metallic particles and their initial catalytic properties in the CO + H2 reaction over Co/Al2O3 catalyst

Formation of Co^o phases with different surface structure over 10 wt% Co/Al₂O₃ and their catalytic properties were induced by pretreatments in H₂ at 570 K for 1 h or 20 h. Electronic behaviour of the Co^o phase, which consists of small (after 1 h reduction) or large bulk-like particles (after 20 h reduction), did not change during the CO hydrogenation after 5 h on stream as was determined by XPS. On the basis of the measured C₂₊ hydrocarbon selectivities the CO molecules are suggested to dissociate on small Co particles to a larger extent than on large cobalt particles. The slight decrease in the catalytic activity with increasing time on stream obtained for the long-term reduced sample is explained by the change in the surface Co^o content detected by XPS. The increase in the catalytic activity along with the change in olefin selectivity, measured for the sample reduced for 1 h, is interpreted by the change of a reaction path involving the Co^o-support interface during the initial period of the reaction.     

Oxidation of ketones over metal oxide catalysts: I. Catalytic synthesis of biacetyl from methyl ethyl ketone

The gas-phase oxidation of methyl ethyl ketone was studied on metal oxide catalysts in the presence of water vapor. Two types of competitive partial oxidations, i.e., biacetyl formation and oxidative scission reaction leading to acetaldehyde and acetic acid, took place on every oxide studied at 400–500 K. An approximate linear relationship was observed between the selectivity of each reaction and the acid-base property of the oxides; the former reaction was accelerated on the basic oxides such as Co₃O₄, while the latter reaction became predominant on the acidic oxides. As Co₃O₄ was the most effective biacetyl former of single-component oxides, modification of Co₃O₄ was examined to develop more effective catalysts for biacetyl synthesis. Scission reaction took the place of biacetyl formation over a catalyst where Co²⁺ ions were located in Y zeolite by an ion-exchanged method. Scission reaction was suppressed when Co oxide was supported on basic oxides such as MgO or CaO; however, the selectivity to biacetyl was slightly decreased due to the occurrence of a new reaction, acetone formation. The addition of Na₂O or Li₂O to Co₃O₄ was found to improve the selectivity to biacetyl without loss of catalytic activity. The maximum efficiency (13%) in biacetyl formation was attained at a Li content of ca. 7 at.%.     

Reducibility and CO hydrogenation over Pt and Pt-Co bimetallic catalysts encaged in NaY-zeolite

Temperature programmed techniques (TPR, TPD) and X-ray diffraction (XRD) have been used to study ion migration and location as well as reducibility of platinum and cobalt ions encapsulated in Pt/NaY, Co/NaY and Pt-Co/NaY zeolites prepared by ion exchange. The temperature required to reduce Co²⁺ in NaY was significantly lowered by the presence of Pt and dependent upon the relative locations of Pt and Co ions in zeolite cages. The exact location was controlled by the calcination condition and the metal contents. For bimetallic catalyst with low Pt content (0.5 wt% Pt and 0.9 wt% Co), the TPR results indicated that reduction of Co²⁺ ions in the vicinity of Pt shifted toward lower temperature, while that of Co²⁺ staying alone was not affected. With high Pt loading (4.5 wt% Pt, 0.7 and 2.6 wt% Co), however, most of the Co²⁺ ions were reduced by means of Pt at temperature below 723 K after calcination at 573 K. The temperature for Pt reduction in bimetallic catalysts was somewhat higher than Pt/NaY and increased with Co atomic fraction, indicating that mixed oxide, PtCo _x O _y , might be formed during calcination. After reduction in hydrogen at 723 K, highly dispersed metal particles were formed. These fine particles were most probably confined inside zeolite cages as indicated by the absence of XRD peak for all samples after calcination and reduction. Surface composition of the bimetallic particles may be different for catalysts with similar Pt content but different Co loading. Accordingly, H/Pt ratios of 1.0 and 0.72 for catalysts with low and high Co content, respectively, were shown by hydrogen chemisorption. It was further supported by the increase in TPD peak intensity with Co loading in the high temperature range, which was related to the reoxidation of Co in bimetallic particles by surface hydroxyl groups. Preliminary results on CO hydrogenation demonstrated that activity and methanol selectivity were higher on Pt-Co bimetallic catalysts than either over monometallic Pt or Co catalyst, which was consistent with the Pt enhanced Co reduction and formation of Pt-Co bimetallic particles.