Higher Alcohol Yield Research Articles

Role of Enzymes in Food Processing

Enzymes are very important in the food industry because they naturally speed up and improve various processes. They are used in many areas, including baking, dairy, brewing, and the processing of fruits and vegetables. Enzymes help make food products better in quality, longer-lasting, more stable, and tastier. In baking, enzymes like amylases, proteases, and lipases are essential. Amylases turn starches into sugars, which feed the yeast and help the dough rise more effectively. Proteases change gluten, making the dough easier to work with. Lipases improve the texture and softness of the bread, helping it stay fresh for a longer time. In dairy processing, enzymes such as rennet and lactase are crucial. Rennet is a mix of enzymes used in cheese-making to coagulate milk, which leads to the creation of curds and whey. Lactase breaks down lactose into glucose and galactose, making dairy products suitable for people who are lactose intolerant. These enzymatic actions not only improve the nutritional value of dairy products but also enhance their digestibility and flavouring, in the brewing industry, enzymes like amylases, proteases, and glucanases are used to convert starches into fermented sugars, break down proteins for better clarity, and lower viscosity. These enzymes help with efficient fermentation, resulting in higher alcohol yields and better beer quality. Additionally, β-glucanase helps break down β-glucans, which can cause problems during filtration, thus improving the overall brewing process. When it comes to processing fruits and vegetables, enzymes such as pectinases, cellulases, and hemicelluloses play important roles. Pectinases break down pectin, a key component of plant cell walls, leading to clearer juices and more efficient juice extraction. Cellulases and hemicelluloses further assist by breaking down cell walls, which helps release valuable nutrients and improves the texture of the processed products. Enzymes are essential in the food processing industry, providing numerous benefits such as better product quality, longer shelf life, increased nutritional value, and greater efficiency in production. Their ability to work under mild conditions, along with their specificity and biodegradability, makes them ideal for sustainable food production. Continuous research and the development of new enzymes and their applications will keep transforming the industry, leading to healthier, safer, and more sustainable food products.

Grades of cassava starch (flours) as sustainable substrates for use in neutral spirit and biofuel production—Industry approach

One way to mitigate the adverse impacts of climate change is through aggressive replacement of fossil energy sources with plant derived renewable energy. The potential of different grades of cassava starch, including decayed cassava starch, as viable alternative and cheaper source of renewable raw materials for bio-ethanol production was studied. The global population keeps expanding and poverty levels keep increasing. Conflict in the use of food-grade cassava starch as raw material for bio-ethanol production will pose a threat to food security. The highest alcohol yield (AY) of 539 LA/t dm was obtained from food grade cassava starch. Food grade cassava starch per-boiled for 5 min produced lower AY (524 LA/t dm). Cassava starch per-boiled for more than 5 min gave much lower AY (507 LA/t). The mildly decayed cassava starch gave a relatively higher AY of 491 LA/t dm than the more decayed cassava substrate that produced AY of 453 LA/t dm. The AY value obtained from the more decayed cassava starch is similar to the AY values obtained with some cereals. Decayed cassava is not fit for human consumption, would not compete with food requirements. This will assist in food security, secure our environment from pollution and other adverse effects.

Electrocatalytic reduction of furfural to furfuryl alcohol using carbon nanofibers supported zinc cobalt bimetallic oxide with surface-derived zinc vacancies in alkaline medium

Electrocatalytic hydrogenation (ECH) reduction provides an environment-friendly alternative to conventional method for the upgrade of furfural to furfuryl alcohol. At present, exploring superior catalysts with high activity and selectivity, figuring out the reduction mechanism in aqueous alkaline environment are urgent. In this work, zinc cobalt bimetallic oxide (ZnMn2O4) with surface-derived Zn2+ vacancies supported by carbon nanofibers (d-ZnMn2O4-C) was fabricated. The d-ZnMn2O4-C exhibited excellent performance in electrocatalytic reduction of furfural, high furfuryl alcohol yield (49461.1 ± 228 µmol g−1) and Faradaic efficiency (95.5 ± 0.5 %) was obtained. In-depth research suggested that carbon nanofiber may strongly promoted the production of adsorbed hydrogen (Hads), and Zn2+ vacancies may significantly lowered the energy barrier of furfural reduction to furfuryl alcohol, the synergistic effect between carbon nanofiber and d-ZnMn2O4 probably facilitated the reaction between Hads and furfuryl alcohol radical, thereby promoting the formation of furfuryl alcohol. Furthermore, the reaction mechanism was clarified by inhibitor coating and isotope experiments, the results of which revealed that the conversion of furfural to furfuryl alcohol on d-ZnMn2O4-C followed both ECH and direct electroreduction mechanism.

Blue, red and white maize as a sustainable resource for production of distilled spirit

The objectives of this research were to explore the potential of blue, red and white maize as sustainable resource for production of distilled spirits and to study the effect and interaction of yeast strains and maize variety on alcohol yield and formation of volatile compounds that are related to the flavor quality. Four maize varieties (yellow, white, blue, and red maize) and four yeast strains (GR-2, DADY, HG-1, and USW-6) were used for distilled spirit production. Blue maize had the highest average alcohol yield (∼90%) and alcohol concentration (12.6%) among the four maize verities. The fermentation efficiency of red maize (89%) was similar to yellow maize (89.3%), while white maize (85.9) was lower than yellow maize. The average alcohol concentration of white maize (11.9%) was similar to yellow maize (12.0%), while red maize (11.5%) was lower that yellow maize. These results show that blue, red and white maize, especially blue maize, are also sustainable resource for spirit production. The type of yeast strains also had significant effect on alcohol yield and concentration. GR-2 achieved consistently the highest average alcohol concentration (12.12%, v/v) and highest alcohol yield (90.16%) regardless of maize variety. HG-1 and USW-6 yielded the similar average alcohol concentration (∼11.94%) and yield (∼88.35%). DADY had the lowest average alcohol concentration (11.84%) and yield (87.62%) among the four yeast strains. Alcohol fermentation also produces other metabolites such as glycerol and lactic acid as the two major byproducts. For all conditions, the lactic acid level was less than 0.1% (v/v) and glycerol level was less than 1.5% (v/v). 1-Butanol, 3-methyl, ethyl octanoate, and ethyl tridecanoate are the indicators of volatile flavor compounds identified in maize raw spirit distillates. These flavors produce maize spirits’ distinctive alcohol, fruity, sweet, and floral flavor profile.

Tuning Co-Cu-Al catalysts and their reaction conditions on the CO2 hydrogenation reaction to higher alcohols under mild conditions

The catalytic conversion of CO2 and H2 into valuable chemicals is a promising alternative to the recent energy and environmental challenges. However, designing an earth-abundant catalyst capable of actively and selectively converting CO2 into desirable products is yet a challenge. Herein, we report on a facile K-Co-Cu-Al catalyst prepared by a coprecipitation method for CO2 hydrogenation to higher alcohols (HAs). We investigated different Co:Cu ratios, reduction temperatures, and reaction conditions (temperature, space velocity, and H2/CO2 ratio) to tune it, enhancing the selectivity and yield of higher alcohols. Co1.8Cu0.9AlOx (1 wt% K), reduced at 400 °C, exhibits a high HAs selectivity of 44.8% (20.8% for ethanol) and space–time yield of 5.54 mmol·h-1·gcat-1 (3.08 mmol·h-1·gcat-1 of ethanol), under mild conditions (250 °C, 30 bar, H2/CO2 ratio of 1.5, and 14200 mL·gcat-1·h-1), which represents one of the best performances among related studies, especially among Co-based catalysts.

Exergy analysis of alternative configurations of biomass gasification-mixed alcohol production system via catalytic synthesis and fermentation

In-depth exergy analysis of three conceptual biomass-mixed alcohol systems using syngas platform has been studied, according to the distribution strategy of synthesis tail gas and syngas. The system configurations are base case, cascade case and parallel case. The results show that higher alcohol yield (C2+OH) is highest in base case, which is a catalytic synthesis process with synthesis tail gas recycling. Yet its exergy efficiency is lower than that of 43.8% in the hybrid conversion configuration of cascade case, of which synthesis tail gas is recycled to an additional subsystem for gas fermentation. And it has increased bioconversion of COX components (CO and CO2) in tail gas for ethanol production under moderate bioreaction condition and biomass carbon utilization ratio of 38.8% is obtained in cascade case. With the detailed exergy analysis at the levels of system, subsystem, and operation component, it highlights that the subsystems of gasification and steam & power generation contribute above 70% of total system exergy destruction, mainly from gasifier and combustor. The results of this study provide a further understanding towards bio-mixed alcohol production configuration to improve its thermodynamic performance as exergy efficiency via the hybrid conversion processes of catalytic synthesis and metabolic fermentation pathway.

Hydrogenation of fatty acids to fatty alcohols over Ni3Fe nanoparticles anchored on TiO2 crystal catalyst: Metal support interaction and mechanism investigation

Catalytic transformation of fatty acids into fatty alcohols is the essential step to produce renewable energy and high-valuable chemicals from waste fatty acids. In this research, a series of Ni3Fe catalysts were synthesized to improve this transformation, specifically that the Ni3Fe anchored on TiO2 surface has performed excellent activity with a high alcohol yield reaching 91.2%. The structure–reactivity relationship between the Ni3Fe nanoparticles on different crystal types of TiO2 (anatase: A-TiO2, rutile: R-TiO2) was investigated. It was found that the as-prepared Ni3Fe/R-TiO2 catalyst showed better catalytic performance than that of Ni3Fe/A-TiO2. Both experimental and density functional theory (DFT) computational results indicated that the interactions between Ni3Fe nanoparticles and R-TiO2 support have highly promoted the formation of oxygen vacancy (Ov), which plays an essential role in CO and HH cleavage, thus promoting the hydrogenation towards fatty alcohols. Furthermore, the catalyst reusability tests showed that Ni3Fe/TiO2 catalyst exhibited good stability over four times recycled and excellent suitability for industrial crude fatty acid conversion.

N-rich doping strategy for constructing Ni@NC catalysts to boost aqueous ethanol coupling towards higher alcohols by inhibiting C1 byproducts

Aqueous coupling of biomass fermentation bio-ethanol offers a promising biorefinery pathway for manufacturing higher alcohols, but it still suffers from the poor utilization efficiency due to the excessive formation of undesired C1 byproducts (CH4, CO and CO2). Herein, N-rich Ni@NC catalysts were synthesized via a facile one-step carbonization of organic–inorganic co-assembly containing polyacrylamide and nickel acetate. Interestingly, the optimized Ni@NC catalyst exhibited excellent performance in aqueous ethanol coupling, giving 74.8 % of ethanol conversion, 49.3 % of C4+ higher alcohol yield and only 1.6 % of C1 gas byproduct selectivity after 12 h reaction at 230 °C. The experimental results and DFT calculations revealed that the regulation of N-rich doping weakened the interaction of Ni with intermediated CH3CHO for inhibiting its deep decomposition into C1 gas byproducts, thereby facilitating the coupling reaction to produce more higher alcohols. Moreover, a feasibility to scale-up the aqueous ethanol coupling was further validated through a 100-fold magnification experiment at ranges of 50–5000 mL, and the fuel properties of higher alcohols as diesel blending were also evaluated. This work opens new avenues for efficient mass-production of higher alcohols via aqueous ethanol coupling.

Efficient Catalytic Upgrading of Ethanol to Higher Alcohols via Inhibiting C–C Cleavage and Promoting C–C Coupling over Biomass-Derived NiZn@NC Catalysts

The conversion of renewable bioethanol into high-energy-density higher alcohols has become essential for meeting the increasing global demand to achieve carbon neutrality. In this study, Zn- and nitrogen-codoped Ni-based lignin-derived carbon catalysts (NiZn@NC) were prepared by solvent volatile self-assembly and in situ reductive carbonization using pulp and paper waste stream alkali lignin as the carbon source. Lignin amphipathic derivatives with −COOH and −NH2 groups would coordinate with metal ions to form a stable lignin–metal framework; thus, the lignin-derived carbon layer disperses the NiZn bimetallic catalyst and prevents from corroding. At an amination reagent/lignin mass ratio of 1:2, an ethanol conversion of 75.2% and a high alcohol yield of 41.7% were achieved over the Ni20Zn1@NC catalyst. Experimental results and density functional theory calculations showed that Zn doping improved the electronic environment and defect structures of metallic Ni and carbon carrier, which effectively inhibited C–C cleavage and suppressed the byproduct formation, such as methane. Thereby, the synergetic effect between Ni and Zn facilitated the efficient conversion of aqueous ethanol into higher alcohols by the Guerbet reaction. This work provides a strategy of in situ pyrolytic doping and stabilizing of renewable biomass macromolecules as the frameworks for the construction of highly active and cost-efficient catalysts for ethanol upgrading.

Optimization of Mashing Parameters Used during the Conversion of Irish Wheat Grain to Spirit Alcohol

The Irish distilling industry is rapidly expanding, diversifying its growth with an increased interest in using different grains in whiskey production. To effectively use Irish-grown wheat in distillation, the identification of cultivars that are suited to the Irish climate and provide high alcohol yields, via a quick screening test for grain alcohol yield that is consistent with Irish industry standards, is required. The current study used response surface methodology (RSM) to optimize mashing parameters, enzyme dosage rate (α-amylase and amyloglucosidase), time, temperature, and malt inclusion rate, using a hard wheat (Triticum aestivum cv. Costello). By optimizing all factors, a maximum alcohol yield (AY) of 471 LA/tonne dry weight basis was achieved, equating to previous research. The enzyme, α-amylase plays a critical part in the process, of converting starch to sugars, and 48 U/g α-amylase was used to reach maximum alcohol yield. Furthermore, an optimal protocol was evaluated on soft wheat cultivars, producing alcohol yields in the range of 483–496 LA/tonne, suggesting the applicability of this product for use across multiple varieties and grain endosperm types. In summary, an optimal alcohol yield methodology was created, with increased AY across four distinct varieties, demonstrating the possibility for Irish cultivated wheat to be used in Irish distilleries.

Construction of Synergistic Co and Cu Diatomic Sites for Enhanced Higher Alcohol Synthesis

Construction of Synergistic Co and Cu Diatomic Sites for Enhanced Higher Alcohol Synthesis

High-efficient production of fatty alcohol via hydrogenation of fatty acid over Cu-NbOx/SBA-15 catalyst

Cu/SBA-15 and Cu-NbOx/SBA-15 catalysts were prepared and evaluated in the hydrogenation of palmitic acid to palmitic alcohol. A high palmitic alcohol yield of 90.8% was obtained using palmitic acid as feedstock. NbOx has been considered to be crucial for the excellent performance and the synergy between Cu and NbOx was well investigated. The interaction between Cu species and NbOx-containing support was studied by various characterizations, such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectra (XPS) and Auger electron spectroscopy (AES). The kinetic data for rate determining step were also collected. The synergistic effect of Cu and NbOx to catalytic activity was discussed and the following insights were obtained: i) the NbOx doping led to form abundant Cu species with more electron-deficient, which is beneficial for the production of alcohol; ii) the oxygen affinity of NbOx promotes the adsorption of oxygen-containing group. Finally, the natural product of palm oil was taken as feedstock and an ideal yield 84.2% of palmitic alcohol was harvested.

The Optimisation of Cooking Parameters for Spirt Whiskey Production from Native Irish Wheat: A Response Surface Method Approach.

Barley and maize have dominated the Irish whiskey sector, but in recent years, alternative grains have started to gain traction. Ireland has a high average wheat yield, producing grain that is high in starch but low in protein, offering the potential for use in distillation. To successfully utilise Irish-grown wheat in distillation, cultivars that are suitable to the Irish climate and give high yields of alcohol need to be identified. This necessitates the development of a rapid screening test for grain alcohol yield. This study examined the optimal temperature, time period, α-amylase dose rate, and calcium concentration to be used in the cooking of wheat grain to maximise alcohol yields. It was determined that lower cooking temperatures are more successful in achieving higher alcohol yields, and it was confirmed that temperature is a key variable in the cooking process. By optimising all parameters, alcohol yields of 458 LA/tonne were obtained, demonstrating that the optimum parameters can be successfully used for both hard and soft endoderm wheat produced in Ireland as well as for different varieties. This indicates potential for producing higher alcohol yields using Irish-grown wheat in Irish distilleries.

MOF-silica hybrid derived high performance K-Cu#SiO2 catalyst for furfural valorization: The functional role of potassium acetate (KAc) in hybridization and copper electronic state

Upgrading biomass platform molecules, e.g. furfural, to value-added fine chemicals has been intensively studied due to its promising potential to substitute the traditional petroleum route producing downstream chemicals. This study presents a high performance K-Cu#SiO2 catalyst derived from the hybrid of copper-based metal-organic-frameworks (Cu-BTC) and silica, for hydrogenation of furfural. The obtained K-Cu#SiO2 having uniformly dispersed copper nanoparticles (~5 nm), achieved a high furfuryl alcohol (FOL) yield (~33 molFOL/molCu h−1), as well as robust recycle utility (trace activity loss after 5 times recycle) at 140 °C and 2.0 MPa. The improved copper metal dispersion and abundant active sites dominating as Cu+/Cu0 species were responsible for the enhanced activity, both of which were closely associated with the functional role of potassium acetate (KAc) serving in the synthesized route. In one respect, the introduced KAc facilitated the Cu-BTC and silica to hybrid a uniform gel by balancing their hydrolysis or crystal growth rates, enabling strengthened copper-silica interactions to yield highly dispersed copper nanoparticles; furthermore, the KAc acted as an electronic regulator to tune the reducibility of copper species on K-Cu#SiO2 catalyst during subsequent N2-calcination. This work could shed a light on the synthesis of high-performance and robust silica-supported copper catalysts for biomass valorization.

Higher alcohol production from ethanol over occluded [Mg4(OH)4]4+ clusters in MgO/KNaX

Conversion of ethanol to higher alcohols was studied over MgO/KNaX, prepared by ion exchange with Mg(OAc)2, followed by KOH washing. The catalysts were characterized by XRF, XRD, SEM, BET, 27Al MAS NMR, EXAFS, NH3- and CO2-TPD. All catalysts showing MgO nanopetals and aggregates on the external surface, contained occluded [Mg4(OH)4]4+ clusters in the zeolite cavities, providing medium basic (Mb) and acid (Ma) sites. Ethanol conversion and higher alcohols selectivity (up to 78%) increased with Mb/Ma ratio due to the increase in both MgO (4–6 wt%) and K (14.7–17.3 wt%) loadings. Decreasing occluded [Mg4(OH)4]4+ clusters and/or increasing MgO aggregates led to the lower conversion and yields of higher alcohols. The essential role of the occluded [Mg4(OH)4]4+ clusters in producing higher alcohols was verified by the reactions using various control catalysts. The MgO/KNaX showed high stability even after steaming at 380 °C, as well as being regenerated by calcination (450 °C in air).

In Situ Hybridizing Cu3(BTC)2 and Titania to Attain a High‐Performance Copper Catalyst: Dual‐Functional Role of Metal‐Support Interaction on the Activity and Selectivity

AbstractProduction of value‐added chemicals sourced from biomass platform molecules has tremendous significance for sustainable chemical engineering. Herein, we reported a successful fabrication of a highly dispersed copper nanoparticles catalyst, CuO#TiO2, via a facile route of in situ homogeneously hybridizing the metal organic framework Cu3(BTC)2 with titania, and subsequent calcination. Distinctly from the copper catalysts prepared by the conventional routes (impregnation or co‐precipitation), this novel CuO#TiO2 catalyst has a small particle size (∼5 nm), easy‐reducible copper species, and weakened Lewis's acidity. As a result, it shows superior high activity (∼20.8 molFUR/molCu ⋅ h) as well as high furfural alcohol yield (>99 %) at 140 °C and 2 MPa for furfural hydrogenation. Moreover, the CuO#TiO2 can be conveniently regenerated by calcination at 200 °C in the air, with no appreciable changes in its structure or activity, a test that we repeated 8 times. Through comprehensive structure characterizations, it has revealed a significant interaction between the CuO and TiO2 originated from the in situ hybridization, which enables a bi‐functional effect on the resulted CuO#TiO2 catalyst: one is to generate more copper active sites by promoting the copper dispersion and reducibility; the other is to hinder the side reactions by decrease the support Lewis acidity. This work demonstrates a practical strategy to rationally design a highly efficient catalytic system in furfural hydrogenation catalysis.

GAT1 Gene, the GATA Transcription Activator, Regulates the Production of Higher Alcohol during Wheat Beer Fermentation by Saccharomyces cerevisiae.

Uncoordinated carbon-nitrogen ratio in raw materials will lead to excessive contents of higher alcohols in alcoholic beverages. The effect of GAT1 gene, the GATA transcription activator, on higher alcohol biosynthesis was investigated to clarify the mechanism of Saccharomyces cerevisiae regulating higher alcohol metabolism under high concentrations of free amino nitrogen (FAN). The availability of FAN by strain SDT1K with a GAT1 double-copy deletion was 28.31% lower than that of parent strain S17, and the yield of higher alcohols was 33.91% lower. The transcript levels of the downstream target genes of GAT1 and higher alcohol production in the double-copy deletion mutant suggested that a part of the effect of GAT1 deletion on higher alcohol production was the downregulation of GAP1, ARO9, and ARO10. This study shows that GATA factors can effectively regulate the metabolism of higher alcohols in S. cerevisiae and provides valuable insights into higher alcohol biosynthesis, showing great significance for the wheat beer industry.

English

Several studies have been conducted in the past using cassava and sweet potato as feedstock to optimise the yield of alcohol. Harvest age of cassava and sweet potato may have some effects on the fermentable carbohydrates quantity. This study aims to establish the best harvest age of cassava and sweet potato for alcohol production. Two varieties of cassava (Sika bankye and Ampong) cultivated and harvested at 8, 10 and 12 months and two sweet potato varieties (Apomuden and Tuskiki) harvested at 3, 4 and 5 months were used for the study. Starch hydrolysis was performed with two sets of enzymes followed by fermentation with Bio-Ferm XR (Lallemand) yeast. The nutrients in Sika bankye were generally higher than in Ampong, except for ash. Sika bankye had the highest alcohol yield (14.8% v/v) between the two cassava varieties, with the best harvest age of cassava for ethanol production being 10 months. Apomuden had relatively higher nutrients than Tuskiki at all levels of growth except for fat. Apomuden had the highest alcohol yield (15.7% v/v) between the two sweet potato varieties with 3 months being the economical harvest age of sweet potato for ethanol production.   Key words: Cassava, sweet potato, harvest age, saccharification, fermentation, alcohol yield.

Combined indigenous yeast strains produced local wine from over ripen Cabernet Sauvignon grape in Xinjiang.

Cabernet Sauvignon grape produced in Xinjiang (China) is often overripe, with unusually high sugar content, which impedes utilization. We aimed to establish the optimal combination of indigenous yeast strains to produce a new sweet wine from the overripe grape. Five yeast strains with pronounced enological characteristics were selected from 88 indigenous yeast isolates. Using a series of co-fermentation experiments with different inoculated strategies, we achieved optimal co-fermentation with a combination of strains SC19 and NS68, later identified as Saccharomyces cerevisiae and Pichia kudriavzevii, respectively, simultaneously inoculated in a 1:1 ratio at the early stage of fermentation. The combination was characterized by vigorous fermentation with high resistance to 457.13g/L sugar and high alcohol yield (16.01% vol). The sweet wine contained 17 aromatic compounds with odor activity value (OAV) ≥ 1 and pronounced sweet fruit, floral, herbaceous, and caramel odors. The co-fermentation has a good potential for utilization of overripe Cabernet Sauvignon grape.

Higher alcohol synthesis from syngas over xerogel-derived Co-Cu-Al2O3 catalyst with an enhanced metal proximity

To improve metal proximity of Co-Cu-Al2O3 catalyst, xerogel-derived mesoporous Co-Cu-Al2O3 catalysts (CoCuAl-Xe) with various Co:Cu molar ratios (3:1, 2:1, 1:1, 1:2, and 1:3) were prepared by an epoxide-driven sol-gel method and applied to higher alcohol synthesis from syngas. The CoCuAl-Xe catalyst induced the formation of a composite spinel structure containing Co, Cu, and Al. At the optimal Co/Cu ratio, the Cu atoms efficiently substituted the Co2+ ions in Co3O4 to form the CuCo2O4 spinel structure. However, an excess amount of Cu induced segregation of CuO, leading to decreasing Co-Cu proximity. In higher alcohol synthesis from syngas, all the catalysts showed the linear quasi-Anderson Schulz Flory plot of carbon-containing products, which was attributed to the CO insertion mechanism in higher alcohol synthesis. Among the xerogel catalysts, 2Co1CuAl-Xe exhibited the highest CO conversion and higher alcohol yield. The Co-rich CoCuAl-Xe catalyst was disadvantageous in terms of alcohol selectivity because of a lack of CO insertion sites, and the Cu-rich one was disadvantageous in CO dissociation and led to methanol formation. The computational study suggests that high Co-Cu proximity favors CHOH* mechanism for CH* formation and promotes CO insertion reaction. Consequently, it was found that the optimal Co/Cu ratio and high Co-Cu proximity is required for high catalytic activity in higher alcohol synthesis.