Mixed Alcohol Synthesis Research Articles

Alternative thermochemical routes for aviation biofuels via alcohols synthesis: Process modeling, techno-economic assessment and comparison

This study presents the conceptual process design for the production of branched paraffins with high carbon number, based on the upgrading of alcohols synthesized from biomass-derived syngas and the economic evaluation and comparison with the Fischer–Tropsh (FT) process and biochemical pathways. Two routes, one based on n-butanol and another on isobutanol upgrading, are described and modeled in ASPENPlus™. The flow sheeting results reveal high performance for both process configurations, resulting in an aviation fuel yield 0.172kg/kgfeedstock and a thermal efficiency of 40.5% in the case of employing a modified Methanol catalyst for the mixed alcohols synthesis (MAS). Such alternative pathways offer higher efficiencies compared to FT synthesis because specific products such as C12+ branched paraffins for jet fuel applications are achieved with higher selectivity in the conversion processes. The water balance at the whole process reveals that the annual demands for fresh water from a 190MWth biorefinery plant are 641,000m3, emerging the water management as an important issue with considerable environmental impacts. Simulations of the overall process show a rather high biomass carbon to product utilization ratio (up to 30%) leading to relative low CO2 emissions. The economic evaluation reveals that the Minimum Jet Fuel Selling Price in a FT plant (1.24€/l jet fuel) is lower than the corresponding price in a MAS plant (1.49€/l and 1.28€/l for cases with different catalysts). The biochemical route based on Acetone–Butanol–Ethanol fermentation is considered as the most economically desirable option (0.82€/l). Moreover, the option of selling organic compounds, which are produced intermediately (i.e. light and heavy olefins, C4 alcohol isomers) via the alcohols’ upgrading processes was proved promising enough for the feasibility of such biorefineries plants.

Effects of cobalt promoter and reduction temperature on the surface species and syngas adsorption of K–Co–Mo/C catalyst for mixed alcohols synthesis

The K–Co–Mo/C catalysts with different molar ratios of Co/Mo and reduction temperatures were prepared by a sol–gel method and characterized by the means of XRD, H2-TPR, XPS and in situ DRIFTS. The addition of moderate amount of cobalt can promote the reduction of Mo species to Moδ+ species. With increasing the Co content, the CO adsorption strength on Moδ+ species increased and was up to the maximum when Co/Mo=0.5. Further increasing the Co content led to the decrease of surface Moδ+ species because that the formation of CoMoO3 inhibited the further reduction of Mo4+ species. Increasing the reduction temperature resulted in the decrease of the surface cobalt content significantly. The CO adsorption strength on Moδ+ species reached a maximum at 773K. Higher reduction temperature caused the decrease of CO adsorption strength because of the sintering of catalyst. It suggested that the surface Moδ+ species is responsible for the alcohol synthesis. The high activity of the K–Co–Mo/C catalysts with Co/Mo ratio of 0.5 for alcohol synthesis should be attributed to its high Moδ+ content on the surface.

Influence of ethylene on the formation of mixed alcohols over a MoS2 catalyst using biomass-derived synthesis gas

Since 2011, a pilot plant for the production of mixed alcohols (MAs) from biomass-derived synthesis gas has been in operation. The pilot plant uses synthesis gas provided by a biomass-based combined heat and power plant (CHP) in Gussing, in which the fixed bed reactor is filled with a sulfidized molybdenum catalyst (MoS2). The advantage of a sulfidized catalyst is resistance to sulfur components. Sulfur resistance significantly lowers the operating costs of such a plant. The main parts of the mixed alcohol synthesis plant in Gussing are a steam reforming unit, a glycol scrubber, a compression step, a fixed bed reactor for the synthesis itself, a condensation vessel for the separation of alcohols from the gas stream, and an expansion valve. The main aim of this project in the last year was to perform parameter variation to investigate the optimal operation point of the plant and to use these parameters to conduct long-time trials over several days. Parameter variation showed the impact of reaction temperature, pressure, and space velocity on product yield and distribution. The influence of the gas composition on the product distribution and side products was also investigated. This study was dedicated to investigating the influence of the ethylene content in the synthesis gas on the formation of propanol and ethyl mercaptan (C2H6S). During the experiments, several liters of MAs were produced. The alcohols consisted mainly of alcohols from carbon numbers between one and three. One of the main results of the first experiments was that the ethylene content in the synthesis gas has a high impact on the product distribution and is also responsible for side reactions to sulfur components.

Effects of Adding Cobalt and Potassium to MoS<sub>2</sub>-based Catalysts on Mixed Alcohol Synthesis

Effects of Adding Cobalt and Potassium to MoS<sub>2</sub>-based Catalysts on Mixed Alcohol Synthesis

Synthesis of mixed alcohols from synthesis gas over alkali and Fischer–Tropsch metals modified MoS2/Al2O3-montmorillonite catalysts

A series of modified MoS2-supported catalysts was investigated for the synthesis of mixed alcohols from synthesis gas in a high-pressure gas–solid flow reaction system. Al2O3-pillared montmorillonite (denoted as Al2O3-Mont) was prepared by calcining [AlO4Al12(OH)24(H2O)12]-pillared montmorillonite at 673 K in air. Al2O3-Mont was an excellent support for MoS2 in the synthesis of mixed alcohols from synthesis gas. The MoS2/Al2O3-Mont catalyst showed a CO conversion of 34.6 % and a selectivity for alcohols of 33.5 % at 553 K under 8 MPa. By introducing 3 wt% K (one of the alkali metals) in MoS2/Al2O3-Mont, the CO conversion increased to 40.5 % and the selectivity for alcohols increased to 41.9 % at 553 K under 8 MPa. Furthermore, by increasing 5 wt% Ni (one of Fischer–Tropsch metals) in KMoS2/Al2O3-Mont, the CO conversion increased to 51.8 % and the selectivity for alcohols increased to 50.5 % at 553 K under 8 MPa. With increasing reaction temperature, the CO conversion and the ratio of C2+ higher alcohols to methanol increased but the selectivity for total alcohols greatly decreased due to the formation of hydrocarbons over KNiMoS2/Al13-Mont under 8 MPa. With increasing reaction pressure, the CO conversion and the ratio of C2+ higher alcohols to methanol increased while the selectivity for total alcohols was almost constant over KNiMoS2/Al13-Mont at 553 K. KNiMoS2/Al13-Mont showed a good catalytic stability in a feed gas containing 10 ppm H2S but gradually deactivated in a clean feed gas due to losing sulfur component during the reaction.

Impact of potassium promoter on Cu–Fe based mixed alcohols synthesis catalyst

Impacts of K promoter on microstructures of a precipitated Cu–Fe based catalyst were studied by N2-physisorption (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and hydrogen temperature-programmed desorption/reduction (H2-TPD/TPR). Mixed alcohols synthesis (MAS) was carried out in a fixed-bed reactor. The results indicated that incorporation of K in the Cu–Fe based catalyst decreased the surface area of the particles, whereas promoted the immigration of bulky iron species to surface layers and strengthened the interaction of surface Fe–Cu. The increase of K concentration weakened the H2 chemisorption and restrained the reduction of both the Cu and Fe species. The catalytic activity and mixed alcohols selectivity increased accompanied with a gradually increasing K concentration, and reached the highest values as the amount of K increased to 0.5wt.%. Subsequently, the MAS activity and selectivity C2+OH presented a decreasing trend. In addition, the increase of K concentration facilitated the formation of heavy hydrocarbons.

Deactivation and stability of K-CoMoSx mixed alcohol synthesis catalysts

Potassium-promoted cobalt molybdenum sulfide (K-CoMoSx) mixed alcohol synthesis catalysts were operated from 118 to 3969h for the purpose of studying catalyst deactivation. Continuous and discontinuous sulfiding with H2S and methyl sulfides was considered. Fresh and discharged catalysts were analyzed via X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). When continuously sulfided, selectivity was maintained for thousands of hours. Without sulfur cofeed, catalysts exhibited a change in selectivity from alcohols to hydrocarbons over periods of hundreds of hours. Sulfur deprivation resulted in oxidization, carburization, and coking of the catalyst surface and segregation of cobalt into crystalline Co9S8. It is suggested that in the absence of a sulfiding agent, the catalyst surface becomes more acidic (oxidized) promoting dehydration of alcohols (selectivity change) and coking (blocking active sites). Reintroduction of H2S may reverse oxidation on non-coked surfaces. Proper sulfur maintenance may render catalysts operable for years without need of regeneration or replacement.

Mixed Alcohol Synthesis over a K Promoted Cu/ZnO/Al2O3Catalyst in Supercritical Hexanes

Mixed alcohol synthesis (MAS) from syngas involves an overall reduction in the number of moles (i.e., volume reduction) and is highly exothermic. As such, the high-pressure, dense-phase solvent conditions of a supercritical reaction medium afford opportunities to enhance the performance of these reactions. In this paper, the effect of supercritical hexanes (a mixture of hexane isomers) on the reaction performance of MAS was studied in a fixed bed reactor. Experiments were carried out over a 0.5 wt % K promoted Cu based mixed metal oxide catalyst in the temperature range of 200 °C–300 °C, a partial pressure of syngas of 4.5 MPa, and the hexanes/syngas molar ratio ranging from 0 to 3. The results of mixed alcohol synthesis under supercritical hexanes phase conditions demonstrated remarkable enhancement in CO conversion and methanol productivity, while the CH4 and CO2 selectivity was notably reduced. In addition, the effect of temperature has also been investigated on conversion, selectivity, and alcohol pro...

The Reverse Water-Gas Shift Reaction and the Synthesis of Mixed Alcohols over K/Cu-Zn Catalyst from CO<sub>2</sub> Hydrogenation

The K/Cu-Zn catalyst has been synthesized by the co-precipitation method coupling with impregnation method and the catalytic performances for the reverse water gas shift (RWGS) reaction and mixed alcohols synthesis from CO2 hydrogenation have been investigated. The catalytic activity and product distribution depend strongly on reaction temperature, pressure, space velocity and the molar ratio of H2/CO2. These results indicated that the optimal conditions for CO2 hydrogenation over K/Cu-Zn catalyst were as follows: 350 K, 6.0 MPa, 5000 h-1 and H2/CO2 = 3.0, under which the selectivity of CO and mixed alcohols reach 84.27 wt% and 7.56 wt%, respectively. The outstanding performances for RWGS reaction and mixed alcohols synthesis of K/Cu-Zn catalyst can be due to the well dispersion of Cu active component.

Mixed Alcohol Synthesis over Sulfided Molybdenum-Based Catalysts

Several alumina-supported molybdenum-based catalysts were prepared by impregnation. The prepared catalysts were characterized using N2 adsorption, X-ray diffraction, temperature-programmed desorption of ammonia, and temperature-programmed reduction with hydrogen. The catalytic activity in mixed alcohol synthesis was evaluated using a fixed-bed pressurized flow reaction system under conditions of 250–320 °C, 3.5–5 MPa, gas hourly space velocity of 280–5000 h–1, and H2/CO ratio of 0.5–1. Effects of reaction conditions, alumina supports, and the addition of potassium were elucidated. The CO conversion and selectivity of the catalysts changed depending upon the calcination temperature of alumina supports that influenced the acid amount of the catalysts. The selectivity of C2+ alcohols eventually reached ca. 40% in the case of calcination temperatures higher than 1000 °C. The selectivity of C2+ alcohols was almost proportional to the addition of potassium that promoted the formation of C2+ alcohols. The selectivity of C2+ alcohols and the chain growth probability of alcohols with potassium carbonate were higher than those with nitrate.

Biochemical and thermochemical conversion of wood to ethanol—simulation and analysis of different processes

Bioethanol as a transportation fuel offers various advantages. It can directly be used in existing transportation options and it can be produced by different conversion routes (i.e. thermochemical or biochemical processes) as well as from various types of feedstock (i.e. biomass containing sugar or starch, lignocellulosic biomass). Especially, the conversion of lignocellulosic biomass promises to improve the environmental performance, e.g. in terms of greenhouse gas emissions, and seems to have a better acceptance compared to sugar- or starch-based processes (i.e. food vs. fuel discussion). However, the process technology for the production of bioethanol from lignocellulosic biomass is still under development. Thus, within this paper, three basic process routes for ethanol from lignocelluloses are analysed from a systems point of view to allow for statements how the further technological development should be directed. For this reason, thermochemical gasification based on wood followed by alcohol synthesis and thermochemical gasification followed by syngas fermentation is compared to a process based on saccharification and subsequent fermentation. This analysis shows that ethanol yields exceeding the theoretical potential based on glucose cannot be reached with the analysed processes. Nevertheless, gasification with syngas fermentation and mixed alcohol synthesis is promising regarding alcohol yields as well as overall energy efficiencies, also compared to other options for liquid biofuels like Fischer–Tropsch diesel or methanol.

Effect of CO2 in the synthesis of mixed alcohols from syngas over a K/Ni/MoS2 catalyst

An unsupported K–Ni–MoS2 catalyst for higher alcohol synthesis from syngas (H2/CO) has been studied during 360h on stream. It shows a gradual increase in activity with time on stream and some possible reasons for this are discussed in the paper. The main focus of this paper was to study the on the effect of CO2-containing syngas, relative CO2-free syngas under identical reaction conditions and identical inlet H2 and CO partial pressures (340°C, 100bar, GHSV=6920ml/(gcath)). The effect of increased partial pressure of H2 and CO was also studied, and to a minor extent also the effect of changed gas hourly space velocity (GHSV). Under the studied conditions, addition of CO2 was found to greatly decrease total product yield, while the selectivities to alcohol and hydrocarbons (C%, CO2-free), respectively, were unchanged. CO2 addition, however, led to a great change in the distribution within the alcohol and hydrocarbon groups. With CO2 added the methanol selectivity increased much while selectivity to longer alcohols decreased. For hydrocarbons the effect is the same, the selectivity to methane is increased while the selectivity to longer hydrocarbons is decreased. It has earlier been shown that product selectivities are greatly affected by syngas conversion level (correlated to outlet concentration of organic products, i.e. alcohols, hydrocarbons etc.) which can be altered by changes in space velocity or temperature. This means that alcohol selectivity is decreased in favor of increased hydrocarbon selectivity and longer alcohol-to-methanol ratio when syngas conversion is increased. At first it might be thought that the selectivity changes occurring when CO2 is present in the feed, just correlate to a decreased organic product concentration in the reactor and that the selectivities with CO2-containing and CO2-free syngas would be identical under constant concentration of organic products in the reactor. However, CO2-addition studies where space velocity was varied showed that significantly lower alcohol selectivity (mainly ethanol selectivity) and increased hydrocarbon selectivity (mainly methane) were found at similar organic outlet concentrations as when CO2-free syngas was feed. Comparing addition of extra H2 or extra CO, it was found that a high H2/CO ratio (H2/CO=1.52 tested in our case) favors maximum product yield, especially methanol formation, while a lower H2/CO ratio (H2/CO=0.66 tested in our case) leads to higher yield of higher alcohols simultaneously minimizing hydrocarbon and methanol formation.

Catalytic conversion of syngas to mixed alcohols over Zn-Mn promoted Cu-Fe based catalyst

Zn-Mn promoted Cu-Fe based catalyst was synthesized by the co-precipitation method. Mixed alcohols synthesis from syngas was studied in a half-inch tubular reactor system after the catalyst was reduced. Zn-Mn promoted Cu-Fe based catalyst was characterized by SEM-EDS, TEM, XRD, and XPS. The liquid phase products (alcohol phase and hydrocarbon phase) were analyzed by GC–MS and the gas phase products were analyzed by GC. The results showed that Zn-Mn promoted Cu-Fe based catalyst had high catalytic activity and high alcohol selectivity. The maximal CO conversion rate was 72%, and the yield of alcohol and hydrocarbons were also very high. Cu (111) was the active site for mixed alcohols synthesis, Fe2C (101) was the active site for olefin and paraffin synthesis. The reaction mechanism of mixed alcohols synthesis from syngas over Zn-Mn promoted Cu-Fe based catalyst was proposed. Zn-Mn promoted Cu-Fe based catalyst can be regarded as a potential candidate for catalytic conversion of biomass-derived syngas to mixed alcohols.

Techno‐economics for conversion of lignocellulosic biomass to ethanol by indirect gasification and mixed alcohol synthesis

AbstractThis techno‐economic study investigates the production of ethanol and a higher alcohols coproduct by conversion of lignocelluosic biomass to syngas via indirect gasification followed by gas‐to‐liquids synthesis over a precommercial heterogeneous catalyst. The design specifies a processing capacity of 2,205 dry U.S. tons (2,000 dry metric tonnes) of woody biomass per day and incorporates 2012 research targets from NREL and other sources for technologies that will facilitate the future commercial production of cost‐competitive ethanol. Major processes include indirect steam gasification, syngas cleanup, and catalytic synthesis of mixed alcohols, and ancillary processes include feed handling and drying, alcohol separation, steam and power generation, cooling water, and other operations support utilities. The design and analysis is based on research at NREL, other national laboratories, and The Dow Chemical Company, and it incorporates commercial technologies, process modeling using Aspen Plus software, equipment cost estimation, and discounted cash flow analysis. The design considers the economics of ethanol production assuming successful achievement of internal research targets and nth‐plant costs and financing. The design yields 83.8 gallons of ethanol and 10.1 gallons of higher‐molecular‐weight alcohols per U.S. ton of biomass feedstock. A rigorous sensitivity analysis captures uncertainties in costs and plant performance. © 2012 American Institute of Chemical Engineers Environ Prog, 2012

Correlation patterns and effect of syngas conversion level for product selectivity to alcohols and hydrocarbons over molybdenum sulfide based catalysts

The focus of the present study was to investigate the effect of the operation conditions, space velocity and temperature, on product distribution for a K–Ni–MoS2 catalyst for mixed alcohol synthesis from syngas. All experiments were performed at 91bar pressure and constant H2/CO=1 syngas feed ratio. For comparison, results from a non-promoted MoS2 catalyst are presented. It was found that the CO conversion level for the K–Ni–MoS2 catalyst very much decides the alcohol and hydrocarbon selectivities. Increased CO conversion by means of increased temperature (tested between 330 and 370°C) or decreased space velocity (tested between 2400 and 18,000ml/(gcath)), both have the same effect on the product distribution with decreased alcohol selectivity and increased hydrocarbon selectivity. Increased CO conversion also leads to a greater long-to-short alcohol chain ratio. This indicates that shorter alcohols are building blocks for longer alcohols and that those alcohols can be converted to hydrocarbons by secondary reactions. At high temperature (370°C) and low space velocity (2400ml/(gcath)) the selectivity to isobutanol is much greater than previously reported (9%C). The promoted catalyst (K–Ni–MoS2) is also compared to a non-promoted (MoS2) catalyst; the promoted catalyst has quite high alcohol selectivity, while almost only hydrocarbons are produced with the non-promoted catalyst. Another essential difference between the two catalysts is that the paraffin to olefin ratio within the hydrocarbon group is significantly different. For the non-promoted catalyst virtually no olefins are produced, only paraffins, while the promoted catalyst produces approximately equal amounts of C2–C6 olefins and paraffins. Indications of olefins being produced by dehydration of alcohols were found. The selectivity to other non-alcohol oxygenates (mostly short esters and aldehydes) is between 5 and 10%C and varies little with space velocity but decreases slightly with increased temperature. Very strong correlation patterns (identical chain growth probability) and identical deviations under certain reaction conditions between aldehyde and alcohol selectivities (for the same carbon chain length) indicate that they derive from the same intermediate. Also olefin selectivity is correlated to alcohol selectivity, but the correlation is not as strong as between aldehydes and alcohols. The selectivity to an ester is correlated to the selectivity to the two corresponding alcohols, in the same way as an ester can be thought of as built from two alcohol chains put together (with some H2 removed). This means that, e.g. methyl acetate selectivity (C3) is correlated to the combination of methanol (C1) and ethanol (C2) selectivities.

Economics of cellulosic ethanol production in a thermochemical pathway for softwood, hardwood, corn stover and switchgrass

The economics of producing cellulosic ethanol using loblolly pine, natural mixed hardwood, Eucalyptus, corn stover, and switchgrass as feedstocks was simulated in Aspen Plus using the thermochemical process via indirect gasification and mixed alcohol synthesis developed by NREL. Outputs from the simulation were linked to an economic analysis spreadsheet to estimate NPV, IRR, payback and to run further sensitivity analysis of the different combinations of feedstocks. Results indicate that forest-based feedstocks including loblolly pine, natural hardwood and eucalyptus may present more attractive financial returns when compared to switchgrass and corn stover, mainly due to their composition (%C, %H, %ash) and alcohol yield. Simulated alcohol yields from forest-based feedstock were significantly higher than from switchgrass and corn stover. Simulations run with switchgrass and corn stover, also demonstrated greater sensitivity to changes in ethanol price, alcohol yield, capital investment and biomass costs. Furthermore, moisture content of receiving feedstocks greatly affected the economics of the biorefinery. A difference of − 10% in the moisture content of the receiving feedstock affected the NPV of the simulated project by + 25% (with respect to central NPV of ~$192 million).

Study of Cu-Fe-Co-M/SiO<sub>2</sub> (M = Unpromoted, Li, Na, K and Cs) Catalysts for Mixed Alcohols Synthesis from CO Hydrogenation

A series of Cu-Fe-Co based catalysts prepared by co-impregnation method using different alkali additives was characterized by BET, XRD and FESEM-EDX and investigated under MAS from CO hydrogenation. The results showed that the catalyst Cu25Fe22Co3-Na3/SiO2 has the highest catalytic activity and selectivity of total alcohol and C5+OH. XRD and FESEM-EDX demonstrated the Na3 catalyst exhibited homogeneous distribution of elements and effective synergy effect between Cu and Fe components, thereby performed good catalytic performances for MAS from CO hydrogenation. The presence of a suitable content of alkali promoter was necessary for mixed alcohols synthesis from syngas.

Adsorption of Potassium on MoS2(100) Surface: A First-Principles Investigation

Potassium- (K-) promoted MoS2 catalyst is a very promising catalyst used for synthesis of mixed higher alcohols from syngas. Herein, periodic density functional theory calculations were performed to investigate the interaction of potassium with the Mo and S edges of the MoS2(100) surface. Both neutral K- and charged “K+”-promoted MoS2(100) systems at different sulfur coverages were studied. Our calculations indicate that the adsorbed K atom readily donates its single 4s valence electron to the MoS2 structure, and the neutral K and charged K+ systems show similar adsorption behavior. Isolated K atom/ion tends to maximize its interactions with the available S atoms on the edge surface, preferring the 4-fold S hollow site on fully sulfided Mo and S edges and the interstitial sites where K atom/ion binds with 2−4 S atoms on the edge surface. The presence of K atoms/ions affects the electronic and magnetic properties of the edge surface. As the K coverage increases, the average adsorption energy of the K atoms...

Energy, water and process technologies integration for the simultaneous production of ethanol and food from the entire corn plant

This paper presents simultaneous integration of different technologies such as the traditional dry-grind process to obtain ethanol from grain with the gasification of the corn stover followed by either syngas fermentation or catalytic mixed alcohols synthesis. The optimal integrated process when using the entire corn plant (18 kg/s of grain and 10.8 kg/s of stover) is the one in which the dry-grind technology to process corn grain is integrated with the catalytic path for the corn stover due to the improved integration of energy, requiring only 17 MW of energy, 50 MW of cooling and 1.56 gal/gal of freshwater, for an ethanol production cost of 1.22 $/gal. However, the production cost decreases as we only use stover to produce ethanol, while the grain is used for food due to the lower cost of the stover and the more favorable energy balance of the ethanol production process from gasification.

Effect of Fe/Co Mass Ratio on Catalytic Performances of Cu-Fe-Co Based Catalysts for Mixed Alcohols Synthesis

采用共浸渍法制备了一系列不同Fe、Co组成的Cu-Fe-Co基混合醇催化剂,对其CO加氢合成混合醇反应性能进行了考察,并采用BET比表面积分析、X射线衍射（XRD）、X射线光电子能谱（XPS）、场发射扫描电子显微镜（FE-SEM）及H_2程序升温还原（H_2-TPR）等手段对其进行了表征.结果表明：Cu-Fe二元催化剂添加适量的Co可以明显提高催化剂醇的明空收率（STY）、CO转化率,而总醇选择性不变.当活性组分Cu、Fe及助剂Co的质量分数分别为25%、22%、3%时,催化剂醇的时空收率高达205.6 g·kg~（-1）·h~（-1）,CO转化率为56.6%.XRD、XPS和TPR结果表明：在Cu组分含量不变时,少量Co组分的引入使催化剂表面形成微量的CuFe_2O_4相,促进了Cu-Fe组分间相互作用的增强,改善了催化剂活性组分的分散度,有利于提高催化剂活性及醇的时空收率;随Co含量的增大,催化剂中金属组分间的相互作用发生转变,形成了Cu-Co尖晶石相,导致催化剂的醇选择性有所下降.