Ethanol Conversion Research Articles

Catalytic Steam Reforming of Ethanol to Produce Hydrogen: Modern and Efficient Catalyst Modification Strategies

AbstractHydrogen is regarded as one of the most promising renewable energy that carriers with a high heating value for replacing fossil fuels and meeting clean energy requirements. Steam reforming has shown considerable promises in the creation of hydrogen. Many studies on catalytic steam reforming of ethanol have been published. Hence, developing efficient and stable catalysts capable of producing large H2 yields and ethanol conversion is a crucial step. Nickel is an essential industrial catalyst because it enhances hydrogenation and dehydrogenation reactions by promoting the scission of C−C bonds. Many studies have been conducted by employing noble metal‐based catalysts to reduce coke deposition and enhance metal stability against sintering since they are known to successfully break the C−C bond, resulting in less carbonaceous deposits and hence more stable catalysts. To avoid carbon production, alkaline promoters, and bimetallic heterogeneous catalysts are commonly utilized in catalysis. However, because huge amounts of by‐product CO2 produced by SRE courses are usually regarded as the primary cause of hydrogen purity degradation, it is recommended to remove CO2 in‐situ to achieve high hydrogen production.

Ethanol Conversion Catalyzed by MCM-22 and Its Dealuminated and Delaminated Forms

The conversion of ethanol into hydrocarbons, particularly into light olefins, was studied over MCM-22 zeolite in their acid form (HMCM-22) and its derived forms obtained by dealumination with oxalic acid (HMCM-22(OA)) and delamination (HITQ-2). The treatment with oxalic acid did not affect zeolite textural properties but reduced the total density and strength of the acid sites. As to the delamination process, HITQ-2 zeolite presented the highest Brunauer, Emmett and Teller (BET) specific area, mesopore volume, and external area, but the microporosity was not affected. This sample showed a lower SiO2/Al2O3 ratio than the precursor HMCM-22, resulting in the highest acid site density but with the predominance of acid sites with weak and intermediate strength. Both dealumination and delamination led to an increase in the number of structural defects in the samples. The comparison of the catalytic performance at 500 ºC showed that despite the differences in the acidic and textural properties of the samples, they were active for ethanol conversion and highly selective for ethylene production. Ethanol conversion, followed by in situ diffuse reflectance spectroscopy (DRIFTS), was also investigated. It showed that, for both samples, the “coke band” intensity was already significant after 1 min of reaction, similar to what was detected for HMCM-22.

Vapour phase Guerbet condensation of ethanol to 1-butanol on CsX zeolite

Nowadays, the conversion of ethanol into valuable chemical products is getting wider application.One of such promising processes is Guerbet condensation of alcohols, which permits the obtaining of 1-butanol from renewable raw materials that are alternatives to petroleum ones.Oxide systems combining acid and basic sites in their composition are promising catalysts for such a transformation.In this study, the efficiency of the magnesium-aluminum oxide and zirconium-oxide catalysts was compared to the activity of the cesium form of X-type zeolite produced by hydrothermal ion exchange in the condensation of ethanol to 1-butanol. The integrity of the zeolite structure was confirmed by using the XRD and XRF analysis, as well as by the IR spectroscopy.The depth of exchange of native sodium for cesium was 82%. It was also found that cesium cations are localized only in ion-exchange positions of faujasite, in places SIII (supercages) and SI` (sodalite cages). CsX zeolite acid to basic sites ratio was found tobe close to optimal for this reaction. Cesium-containing zeolite at 300 °C showsethanol 35-55 % conversion and 20-25 % selectivity for 1-butanol, which is higher than the same characteristics for zirconium samples, but slightly inferior to magnesium-aluminum oxide catalysts. The obtained results indicate the promising use of zeolites of a similar nature in the process of condensation of ethanol to 1-butanol.

Alkali carbonate induced N-doped NiSn@NC for direct aqueous ethanol coupling to C6+ higher alcohols.

Synthesis of C6+ higher alcohols from readily-accessible aqueous ethanol is an alternative route of great potential for blending-fuel, plasticizer, surfactant and medicine precursors, but the direct coupling of aqueous ethanol to C6+ higher alcohols is still challenging. Herein, the alkali carbonate induced N-doping of a NiSn@NC catalyst was achieved by a facile gel-carbonization strategy, and the effect of alkali salt inductors was examined for the direct coupling of 50 wt% aqueous ethanol. Noteworthily, C6+ higher alcohol selectivity of 61.9% with 57.1% ethanol conversion was achieved for the first time over the NiSn@NC-Na2CO3-1/9 catalyst, which broke the step-growth carbon distribution of ethanol coupling to higher alcohols. The inductive effect of alkali carbonate for the N doped graphite structure from the NO3- precursor was revealed. Electron transfer from Ni to the pyridine N doped graphite layer is enhanced, thus elevating the Ni-4s band center, which lowers the dehydrogenation barrier of the alcohol substrate and further improves the C6+OH selectivity. The catalyst reusability was also examined. This work gained new insight into the selective synthesis of high-carbon value-added chemicals from C-C coupling of aqueous ethanol.

Mechanistic insights into CeO2-catalyzed direct synthesis of diethyl carbonate from CO2 and ethanol assisted by zeolite and 2,2-diethoxypropane

A mechanistic study on the production of diethyl carbonate on a CeO2 catalyst assisted by H-FAU and 2,2-diethoxypropane was conducted based on detailed kinetics.

DEPENDENCE OF THE ACTIVITY OF Ce-Zn-O CATALYSTS IN THE REACTION OF THE CONVERSION OF ETHANOL INTO ACETONE ON THE ACIDIC PROPERTIES OF THE SURFACE

The reaction of ethanol conversion to acetone on binary cerium-zinc oxide catalysts has been studied. It has been established that the reaction products of the conversion of ethyl alcohol on binary cerium-zinc oxide catalysts are ethylene, acetaldehyde, acetone, carbon dioxide and, at high temperatures, destructive decomposition products. The highest yield of acetone is observed on samples rich in zinc at temperatures of the order of 450-550°C, while catalysts rich in cerium are active in the reaction of dehydration of ethanol to ethylene. In this work, the acid properties of cerium-zinc oxide catalysts were evaluated by their activity in the isomerization of butene-1 to trans and cis butenes-2. It was found that cerium-rich catalysts are active in butene-1 isomerization reaction. The activities of cerium-zinc oxide catalysts in the reactions of the conversion of ethanol to acetone and the isomerization of butene-1 into trans and cis butenes-2 are compared. It was found that the reaction of the conversion of ethanol to acetone proceeds on the centers of the basic nature, and the formation of ethylene proceeds on the centers of the acidic nature.

A study of the conversion of ethanol to 1,3-butadiene: effects of chemical and structural heterogeneity on the activity of MgO–SiO2 mixed oxide catalysts

MgO–SiO2 catalysts were synthesized by using non-porous and mesoporous MgO for ethanol to butadiene reaction. Significantly higher butadiene yields were achieved over mesoporous MgO based catalysts.

Effect of alkali metal addition on catalytic performance of Ag/ZrO2/SBA-16 catalyst for single-step conversion of ethanol to butadiene

Alkali addition to a Ag/ZrO2/SBA-16 system for ethanol to butadiene affects a beneficial decrease in Lewis acid sites, mitigating ethanol dehydration. This results in remarkable butadiene selectivity and superior productivity over the lifetime study.

Length-tunable Pd2Sn@Pt core-shell nanorods for enhanced ethanol electrooxidation with concurrent hydrogen production.

The electrooxidation of ethanol as an alternative to the oxygen evolution reaction presents a promising approach for low-cost hydrogen production. However, the design and synthesis of efficient ethanol oxidation electrocatalysts remain key challenges. Here, a colloidal procedure is developed to prepare Pd2Sn@Pt core-shell nanorods with an expanded Pt lattice and tunable length. The obtained Pd2Sn@Pt catalysts exhibit superior activity and stability for ethanol electrooxidation compared to Pd2Sn and commercial Pt/C catalysts. By tuning the length of the Pd2Sn@Pt nanorods, remarkable mass activity of up to 4.75 A mgPd+Pt-1 and specific activity of 20.14 mA cm-2 are achieved for the short nanorods owing to their large specific surface area. A hybrid electrolysis system for ethanol oxidation and hydrogen evolution is constructed using Pd2Sn@Pt as the anodic catalyst and Pt mesh as the cathode. The system requires a low cell voltage of 0.59 V for the simultaneous production of acetic acid and hydrogen at a current density of 10 mA cm-2. Density functional theory calculations further reveal that the strained Pt shell reduces energy barriers in the ethanol electrooxidation pathway, facilitating the conversion of ethanol to acetic acid. This work provides valuable guidance for developing highly efficient ethanol electrooxidation catalysts for integrated hydrogen production systems.

Heteroatom zeolites with a high content of framework metal sites as Lewis-acid catalysts for the conversion of ethanol–acetaldehyde to 1,3-butadiene

Heteroatom zeolites with a high content of framework metal sites as Lewis-acid catalysts via improved dissolution–reconstruction strategy.

Isolation and Characterization of Microorganisms From Scoby (Symbiotic Culture of Bacteria and Yeast) During Kombucha Fermentation

Kombucha is made by fermenting tea with sugar solution using SCOBY (symbiotic culture of bacteria and yeast). Kombucha fermentation is divided into several stages, such as the conversion of sugar into ethanol, the conversion of ethanol into acetic acid, and the conversion of acetic acid into carbon dioxide. Thus, several types of unique microorganisms must be involved during kombucha fermentation. Our previous research has reported that culturable microorganisms from kombucha drink (liquid phase) were all bacteria. Furthermore, in this research we investigated culturable microorganisms from the SCOBY itself. During kombucha fermentation, SCOBY sheets were cut (about 1×1 cm) each day using a sterile knife. SCOBY slice was enriched in Potato Dextrose Broth and incubated at 37 °C for 24 hours. The enriched culture was inoculated into Plate Count Agar and incubated at 37 °C for 24 hours. Four different colonies, named isolate (a), (b), (c), (d), were collected during 14 days of kombucha fermentation. The suspected colonies of bacteria were cultivated in Nutrient Agar, while the suspected colonies of mold or yeast were cultivated in Potato Dextrose Agar. The characterization results suggested that isolate (a) has close characteristic to Acetobacter genus (gram negative, short rod, does not produce endospore), meanwhile isolate (b) is gram negative, long rod, and produces endospore. Isolate (c) was suspected as mold, and isolate (d) was identified as yeast.

The role of crystalline phase of zirconia in catalytic conversion of ethanol to propylene

Zirconia catalysts can selectively convert ethanol to propylene and exhibit excellent catalytic stability. However, the effects of crystalline phase of ZrO2 on the catalyst active sites and catalytic performance have not been fully recognized. In this work, when Y or La was doped into ZrO2, the monoclinic to tetragonal phase transition occurred, and the propylene yields were improved to 44.0% and 42.3%, respectively. The effects of different crystalline phases of ZrO2 on the ethanol to propylene reaction were analyzed by density functional theory. Comparing the monoclinic, tetragonal and cubic phases of ZrO2, the tetragonal phase ZrO2 has the lowest oxygen vacancy formation energy and is likely to form oxygen vacancies to convert ethanol to propylene. Moreover, the adsorption energy of ethanol on tetragonal ZrO2 is moderate, which is not only beneficial to ethanol conversion, but also reduces catalyst deactivation caused by excessive adsorption. Therefore, tetragonal ZrO2 shows practical significance for catalyzing ethanol to propylene.

Boosting the selectivity of higher alcohols in upgrading of aqueous bioethanol over amphiphilic NiSn@C-MgO catalyst

Bio-ethanol produced from biomass has been regarded as a promising feedstock for producing higher alcohols (C4+ alcohols) through the Guerbet route. Nevertheless, the high-efficiency upgrading of bio-ethanol is driven by the current disadvantage of low selectivity to C6+ alcohols. Herein, we designed and synthesized an amphiphilic NiSn@C-MgO, which was composed of NiSn nanoparticles (NPs) coated with carbon shell and MgO nanoflakes support. Detailed experiments reveal that the amphiphilic NiSn@C-MgO catalyst can stabilize emulsions and facilitate the cross-coupling of ethanol and C4+ alcohols (generated by ethanol self-condensation) to generate C6+ alcohols in aqueous ethanol upgrading. Furthermore, the carbonization temperature has a great influence on the structure of NiSn@C-MgO, thus greatly affecting the catalyst performance. Consequently, the optimal NiSn@C-MgO-550 displays an excellent activity with ethanol conversion of 73.3 %, the selectivities of C6+ alcohols and C8+ alcohols in liquid products also reach up to 60.9 % and 32.5 %, respectively. This present strategy provides an efficient strategy for the direct upgrading of water-containing bio-ethanol to desired biofuel components, which may promote the fundamental researches on the production of biorefineries and green fuels.

Ni and Co-based catalysts supported on ITQ-6 zeolite for hydrogen production by steam reforming of ethanol

Ni and Co catalysts supported on ITQ-6 zeolite have been synthesized and evaluated in the steam reforming of ethanol (SRE). Catalysts were also characterized by means of N2 adsorption-desorption, XRD, H2-TPR, and H2-chemisorption. ITQ-6 containing Co (Co/ITQ-6) presented a higher conversion of ethanol and production of hydrogen than ITQ-6 containing Ni (Ni/ITQ-6). The lower size of the metallic cobalt particles shown in Co/ITQ-6 seems to be the major responsible of its higher catalytic performance. Regarding the reaction by-products (CO, CH4, C2H4O and CO2), Co/ITQ-6 showed the lowest selectivity at medium and high temperatures (773 and 873 K). At low reaction temperatures (673 K) the dehydrogenation reaction predominates in the Co/ITQ-6, what it is supported by the high concentration of acetaldehyde detected at this temperature. In the case of the Ni/ITQ-6 the main side reaction at 673 K seems to be the methanation reaction since large concentrations of methane are detected. Stability studies were also carried out showing lower deactivation of Co/ITQ-6 at large reaction times (24 h). Characterization of the exhausted catalysts after reaction showed the presence of coke in both catalysts. Nevertheless, Co/ITQ-6 presented the lowest coke deposition. In addition, Co/ITQ-6 exhibited the lowest metal sinterization, what could be also account for the lower deactivation exhibited by this sample. This fact could be related to the higher interaction between the cobalt metallic particles and the ITQ-6 support as the H2-TPR studies demonstrate.

Study on C4 olefin production by ethanol coupling based on multiple regression model

In this paper, the influencing factors of ethanol conversion, C4 olefin selectivity and C4 olefin yield in the experiment of ethanol coupling preparation were analyzed, and then quantified modeling was carried out, and the combination design of catalyst was carried out, so as to make the above three variables reach the optimal value.Using the experimental data, professional and statistical analysis methods were used to analyze the correlation and regression of the possible influencing factors.On the basis of the experimental data given in the research background, the optimal catalyst combination and temperature for the above targets in the process of preparing C4 olefin were obtained.

Multi-size distributed Ni catalyst embedded in SiCxOy film by inverse microemulsion-precipitation method for ethanol steam reforming

Ni/SiCxOy catalysts with multi-size distribution of Ni particles, were prepared and supported on porous SiC ceramics by a combination of inverse microemulsion and precipitation methods, as reaction microchannels for ethanol steam reforming (ESR). The microstructure, phase composition, reduction performance, hydrogen production performance of ESR, and the type and growth of carbon deposition were investigated for Ni/SiCxOy catalysts. The Ni catalysts embedded in SiCxOy film with the appropriate amount of precipitant exhibited multi-size distribution and minimal particle size. The initial ethanol conversion rate and H2 selectivity of Ni/SiCxOy catalysts during ESR reaction were 100% and 75%, respectively, remaining 95% and 69.2% after 20 h, respectively. Raman and SEM results indicate that Ni/SiCxOy catalysts with appropriate amounts of precipitant tended to grow more loosely arranged carbon nanowires. The combination of inverse microemulsion and precipitation methods produced smaller and multi-size distributed Ni/SiCxOy catalysts with superior durability and hydrogen production performance in ESR reaction.

Selectivity of Ethanol Conversion on Al/Zr/Ce Mixed Oxides: Dehydration and Dehydrogenation Pathways Based on Surface Acidity Properties

AbstractZirconia‐alumina mixed oxides (Zr+Ce)O2−Al2O3 with various mol. ratios (5, 10, 20, 50, and 75 % alumina) were prepared using the sol‐gel method. The catalysts were characterised via XRD, SEM, DTA/TG, BET, and FT‐IR spectroscopy. The acidities of the catalysts were measured through the absorption of anthraquinone and pyridine probe molecules using EPR and IR spectroscopy, respectively. Catalytic activity and selectivity were investigated for ethanol conversion to acetaldehyde, ethylene, and diethyl ether, which were used as model reactions to identify surface‐active sites. The relationship between the surface structure and the dehydration/dehydrogenation activity was evaluated. Diethyl ether formation is promoted by the presence of the ZrO2 tetragonal phase at a low ZrO2/Al2O3 ratio in the sample composition, at which the Lewis acid site has an aluminum‐oxygen environment. The reaction mechanism was also discussed. In the low‐temperature reaction region, dehydrogenation competes with dehydration; ethylene and acetaldehyde share a common reactive intermediate.

Study on Preparation of Olefins by Coupling ethanol based on partial correlation Analysis and Linear stepwise regression

. A correlation analysis was constructed according to the effect of catalyst and temperature on the chemical reaction in the reaction of ethanol coupling to C4 olefin. Firstly, the relationship between the reaction product, temperature, and the reaction product was explored. The chemical mechanism analysis and qualitative image analysis inferred that temperature is related to ethanol conversion and C4 olefin selectivity. Then the Pearson correlation coefficients of each group of temperatures and the corresponding experimental data are calculated, and 90% of the correlation coefficients are greater than 0.9. it is confirmed that they have a significant positive correlation.

Role of low carbon emission H2 in the energy transition of Colombia: Environmental assessment of H2 production pathways for a certification scheme

• Carbon footprint threshold for H 2 production in Colombia. • Stakeholders for the low carbon emission, high-quality H 2 certification scheme in Colombia. • Emission threshold of green-H 2 determined as 4.13 kg CO 2 -eq/kg H 2. • Green-H 2 from biomass gasification is environmentally friendly. • Installed wind and solar energy capacities must be increased to meet the low carbon-H 2 demand. Hydrogen (H 2 ) is a low-carbon carrier. Hence, measuring the impact of its supply chain is key to guaranteeing environmental benefits. This research proposes a classification of H 2 in Colombia based on its carbon footprint and source. Such environmental characterization enables the design of regulatory instruments to incentivize the demand for low carbon-H 2 . Life cycle assessment (LCA) was used to determine the carbon footprint of H 2 production technologies. Based on our LCA, four classes of H 2 were defined based on the emission threshold: (i) gray-H 2 (21.8 - 17.0 kg CO 2 -eq/kg H 2 ), (ii) low carbon-H 2 (4.13 – 17.0 kg CO 2 -eq/kg H 2 ), (iii) blue-H 2 (<4.13 kg CO 2 -eq/kg H 2 ), and (iv) green-H 2 (<4.13 kg CO 2 -eq/kg H 2 ). While low carbon-H 2 could be employed to reduce 22% of the national greenhouse gas (GHG) emissions as defined in the National Determined Contribution (NDC), both blue and green-H 2 could be employed for national and international trade since the standard emissions are aligned with international schemes such as CertifHy and the Chinese model. Besides, gasification of biomass results in environmental savings, indicating that biomass is a promising feedstock for international and local trade. Furthermore, combinations of H 2 production technologies such as renewable-based electrolysis, natural gas steam reforming with CCS, and ethanol conversion were evaluated to explore the production of a combination of green- and blue-H 2 to meet the current and future demand of low carbon emission H 2 in Colombia. However, to comply with the proposed carbon emission threshold, the installed capacities of solar and wind energies must be increase.

New iron-containing MFI-type zeolites in the catalytic conversion of ethanol, propane, and N2O

New iron-containing MFI-type zeolites in the catalytic conversion of ethanol, propane, and N2O