Condensation Of Acetaldehyde Research Articles

Synergistic Catalysis by MgO Induced Acid‐Base Bifunctional Sites for Cross Condensation of HCHO and Acetaldehyde

Acid‐base synergistic catalysis greatly enhances the performance of MgO‐based catalysts in the Aldol condensation. Here, the effect of acid‐base strength/concentration/proportion and the synergistic catalysis on the performance of cross condensation between HCHO and acetaldehyde were studied. The NH3/CO2‐TPD results suggested that weak acidic sites combined with medium basic sites were beneficial for the cross condensation. The loading of MgO nanocrystals on SiO2 induced the generation of new acidic sites (Mg‐O‐Si). Combined with the inherent basic sites (Mg‐O‐Mg) and Mg‐O‐Si, the acid‐base bifunctions sites could catalyse the cross condensation of HCHO and acetaldehyde synergistically. The appropriate proportion of acidic/basic sites (10/1) is critical for the cross condensation in the presence of vast water in formalin. The effect of reaction parameters, including the molar ratio of substrates, reaction temperature, liner velocity and weight hourly space velocity, were investigated for the cross condensation. The results showed that 10 wt% MgO/SiO2 catalyst possessed the highest catalytic activity (57.9% conversion of acetaldehyde and 84.3% selectivity of acrolein) under the optimal reaction parameters among the investigated catalysts. The MgO/SiO2 can be reused and recovered its catalytic performance after in‐situ regeneration in air to remove the carbon deposition.

Deactivation mechanism of acetaldehyde self-condensation on Zr-based metelliosilicalites

Zr-BEA zeolite was introduced to the aldol condensation of acetaldehyde and showed high crotonaldehyde selectivity (over 85%), but it suffered from rapid deactivation, where the conversion of acetaldehyde decreased from 16.4% at 1 h to 6.5% at 8 h. The spent Zr-BEA zeolites at different time-on-stream (TOS = 1, 2, 4, 6, and 8 h) were characterized by SEM, XRD, XPS, FT-IR, TGA, N2 physical adsorption, and GC–MS to understand the deactivation mechanism. Pore blocking and Zr active site coverage caused by carbonaceous deposits were both responsible for the deactivation. Furthermore, the main carbonaceous species were unsaturated aldehydes, unsaturated ketones, and aromatic compounds.

Effect of an amine-aldehyde condensate modifier on the thermal and mechanical properties of fiber-reinforced epoxy composites

Purpose The manufacture of polymer composites with a lower environmental footprint requires incorporation of sustainably sourced components. In addition, the incorporation of novel components should not compromise the material properties. The purpose of this paper is to demonstrate the use of a synthetic amine functional toluidine acetaldehyde condensate (AFTAC) as a modifier for fiber-reinforced epoxy composites. One of the fiber components was sourced from agricultural byproducts, and glass fiber was used as the fiber component for comparison. Design/methodology/approach The AFTAC condensate was synthesized via an acid-catalyzed reaction between o-toluidine and acetaldehyde. To demonstrate its efficacy as a toughening agent for diglycidyl ether bisphenol A resin composites and for the comparison of reinforcing materials of interest, composites were fabricated using a natural fiber (mat stick) and a synthetic glass fiber as the reinforcing material. A matched metal die technique was used to fabricate the composites. Composites were prepared and their mechanical and thermal properties were evaluated. Findings The inclusion of AFTAC led to an improvement in the mechanical strengths of these composites without any significant deterioration of the thermal stability. It was also observed that the fracture strengths for mat stick fiber-reinforced composites were lower than that of glass fiber-reinforced composites. Originality/value To the best of the authors’ knowledge, the use of the AFTAC modifier as well as incorporation of mat stick fibers in epoxy composites has not been demonstrated previously.

Catalyst deactivation of cation‐exchange resin in cross‐aldol condensation of acetaldehyde to methyl pentenone

AbstractThe aldol condensation of acetaldehyde with methyl ethyl ketone was studied for the production of methyl pentenone in the presence of cationic resin, Amberlyst‐15. Methyl pentenone (MPO) is an important intermediate used for the synthesis of Iso‐E‐Super, which is a precursor in sandalwood fragrances. Amberlyst‐15 used as an alternative heterogeneous catalyst for conventional corrosive sulphuric acid was found to get deactivated with prolonged use. In this work, major possible causes of catalyst deactivation, such as desulphonation, coking, grafting, metal deposition and thermal degradation, are investigated. Characterization of fresh and used catalysts is performed for surface area, mass deposited and elemental composition (CHNS and ICP). The results confirm that multiple causes, i.e., desulphonation, metals exchange and oligomers deposition, are responsible for the catalyst deactivation. The presence of metal promotes desulphonation; the desulphonation along with metal exchange appears to be the major contributors to catalyst deactivation; and avoiding exposure to metal impurities may enhance the catalyst life significantly. Catalyst regeneration was also explored, and the catalyst site density is reclaimed from 0.5–0.6 meq/g to 4.1–4.2 meq/g, which is closer to the fresh Amberlyst‐15 (4.5–4.6 meq/g). The study provides a way to develop the resin‐based green technology for catalytic reactions.

Direct ethyl acetate synthesis from ethanol over amorphous-, monoclinic-, tetragonal ZrO2 supported copper catalysts prepared from the same zirconium source

Direct ethyl acetate synthesis from ethanol was examined by supported Cu catalysts on various kinds of acid-base metal oxides, available ZrO2-based oxides, and homemade amorphous-, monoclinic- and tetragonal zirconia prepared from the same Zr source. XRD, XAFS, TG-DTA characterization and surface area measurement were performed. Effects of crystalline phase of ZrO2 support on selective ethyl acetate production was discussed based on the yields and products ratio (ethyl acetate to sum of C4-alcohols and aldehydes). Based on catalytic performance by 29 kinds of homemade catalysts, amorphous-type ZrO2 was found to be essentially the most suitable ZrO2 phase for the selective ethyl acetate formation in cases without any surface modifications. The acid site on the surface of monoclinic-type ZrO2 catalysts possibly promoted unfavorable acetaldehyde condensation reaction, but addition of Na+ for poisoning could increase selectivity of ethyl acetate formation. Coordination environment of Cu species for fresh and spent catalysts were discussed.

STUDIES ON THE ALKYLATION OF QUINIZARIN

Quinizarin a precursor to anthracyclines was subsequently alkylated with α, β-unsaturated aldehydes - crotonaldehyde, acrolein and ethyl acrylate using piperidinium acetate as a catalyst and ethanol as solvent. Quinizarin was synthesized using phthalic anhydride and parachlorophenol with concentrated sulphuric acid as solvent and catalyst in synergism with boric acid at 2600C to give a yield of 36.3%, then reduced to leucoquinizarin using Sn in concentrated hydrochloric acid with glacial acetic acid as solvent and refluxed for five hours to give a yield of 35.6%. The alkylating reagent crotonaldehyde was synthesized by aldol condensation of acetaldehyde with concentrated sulphuric acid as catalyst at a yield of 27.1% while acrolein was synthesized by the dehydration of glycerol using potassium bicarbonate as catalyst at a yield of 94.8%. Leucoquinizarin was alkylated with crotonaldehyde, acrolein and ethyl acrylate using piperidinium acetate as a catalyst in ethanol. The alkylation with crotonaldehyde and ethyl acetate was done by reflux for three and five hours respectively and resulted in a 1, 4 addition and a subsequent aldol annelation reaction accompanied by a 1,3 sigmatropic shift to give a pentacyclic ring at a yield of 42.1% and 61% respectively. Acrolein gave a polymeric product.

Aldol condensation of acetaldehyde for butanol synthesis: A temporal analysis of products study

The catalytic upgrading of CO2-based ethanol into valuable products, such as higher alcohols, is of increasing interest. Carbon-neutral n-butanol can substitute major fractions of conventional gasoline in the transport sector of the future. A promising synthesis path towards n-butanol is the Guerbet reaction, in which the homo aldol condensation of acetaldehyde constitutes an important intermediate step, which was investigated using the Temporal Analysis of Products methodology. This investigation employed the lanthanide oxides Dy2O3, Eu2O3, and Er2O3, supported on activated carbon due to their varying basic characteristics. In addition to the aldol condensation of acetaldehyde yielding butanol, its decomposition into CO, CH4, and H2 also occurred. Furthermore, acetaldehyde pulsing onto the catalyst surface of Dy2O3/C also lead to the formation of carbonaceous deposits. Fortunately, catalyst regeneration by means of O2 pulsing was successful. Other reaction routes yielding acidic acid, ethyl acetate, or diethyl ether could be experimentally excluded.

Process optimization for biosynthesis of pyruvate decarboxylase (PDC) and Neuberg’s ketol (PAC) from a novel Pichia cecembensis through response surface methodology

PurposePhenylacetylcarbinol (PAC) is an intermediate for the synthesis of several active pharmaceutical ingredients (ephedrine, pseudoephedrine, norephedrine, etc.) used for the production of antiasthematics and decongestants. An efficient biosynthesis of PAC through condensation of benzaldehyde and acetaldehyde catalyzed by a solvent tolerant pyruvate decarboxylase (PDC) is being reported. A process for the biosynthesis of PAC was designed and optimized through response surface methodology (RSM) in the present study.MethodsThe effects of incubation time (8–18 h), incubation temperature (30–38 °C), medium pH (4–10), and inoculum size (4–10%) on PAC yield, sugar consumption, and PDC activity were determined through submerged fermentation using a newly isolated potent yeast strain of Pichia cecembensis. PAC was quantified spectrophotometerically and through HPLC. PDC produced was exposed to 40 mM benzaldehyde as whole cells, crude extract, and partialy purified preparation to check its stability against the said solvent.ResultsThe highest PDC activity and PAC yield during present study were found to be 56.27 U/ml and 8.44 g/l, respectively. The yield of PAC was increased by 71% (2.22 to 8.44 g/l) after process optimization through RSM with incubation time of 13 h, incubation temperature of 33 °C, and 18% total sugar as significant factors (P-values, 0.902, 0.260, and 0.247, respectively). R-squared value of 0.770 and Adeq Precision value of 4.888 show the goodness of fit of the process design. PDC is used in the form of Pichia cecembensis whole cells revealed higher stability towards benzaldehyde and elevated temperature as compared to partially purified PDC. Whole cells and partially purified PDC showed half-lives of 240 and 72 h at 4 °C, whereas 33 and 28.5 h at 25 °C. PAC was purified though HPLC with a purity level of 76.18%.ConclusionIncubation time, temperature, and sugar concentration were found to be significant factors for the biosynthesis of PAC. A newly isolated Pichia cecembensis produced a highly active, solvent, and temperature-tolerant pyruvate decarboxylase (PDC) which is superior to its counterpart being presently used in the industry. Hence, this novel yeast species is a promising candidate for commercial production of PAC and other related APIs owing to its highly stable PDC.

One‐Step Synthesis of Sulfate‐Modified Titania Nanoparticles with Surface Acidic and Sustained Photocatalytic Properties via Solid‐State Thermolysis of Titanyl Sulfate

AbstractTitania nanoparticles surface‐functionalized with sulfate were prepared by thermal degradation of titanyl sulfate. At 600 °C pure anatase phase is obtained. X‐ray photoelectron spectroscopy (XPS) showed 1.4 at.% sulfur in the +6 oxidation state. At 700 °C anatase was still present, which is attributed to the presence of small amounts of stabilizing sulfate groups only detectable by high‐resolution XPS, segregating to the nanoparticle interfaces. Adsorption and photocatalytic degradation of acetaldehyde reactions were studied by in situ diffuse reflectance Fourier transform spectroscopy and 2D correlation spectroscopy, and compared with pure anatase nanoparticles. Aldol condensation of acetaldehyde and subsequent accumulation of crotonaldehyde was lower on sulfate‐modified titania. Butanoate was identified as an intermediate, which forms after dimerization and aldol condensation. Much more carboxylates and carbonates accumulated on pure anatase catalysts compared with sulfate‐modified anatase during photocatalysis. It is conjectured that surface acidic photocatalysts could be beneficial for achieving sustained activity for photodegradation of organic pollutants.

(Invited) Electrochemical Reduction of Carbon Dioxide to Oxygenates and Hydrocarbons

Currently, more than 80% of the world’s energy needs are met by burning fossil fuels. Supplies of these fuels are intrinsically limited and will eventually run out. Combustion of fossil fuels also generates carbon dioxide, whose rapidly increasing atmospheric concentration contributes to global warming. One solution for mitigating atmospheric concentrations of CO2 is to electrochemically reduce these molecules into chemicals and fuels. If the energy used for these processes is generated from renewable sources such as solar and wind, we can envisage a chemical production cycle that is closed-loop with net zero carbon emission.In this talk, we share our recent works related to the development of catalysts for the selective electroreduction of CO2 to oxygenates and hydrocarbons. We shall show the pathway by which CO2 could be converted to 1-butanol, a C4 alcohol. Through a series of control experiments and density functional theory (DFT) calculations, we pinpoint that its C4 backbone was formed from a surface-mediated aldol condensation of acetaldehyde formed from CO2 reduction, rather through the coupling of four CO intermediates. We also discuss how CO2 could be reduced to methanol through a tandem process - CO2 was first reduced to formic acid, and the latter can be reduced to methanol using anodized titanium. For the latter step, experiments and DFT calculations identify Ti3+ and oxygen vacancies (TOV) as the active sites in a vacancy-filling pathway mediated by *H2COOH. We also give screening rules based on the *HCOOH and *H2COOH binding energies alongside TOV formation energies. These can facilitate the high-throughput automated design of catalysts for CH3OH synthesis from tandem CO2 electrolysis. In the last part of our talk, we show how molecules not commonly observed during CO2 reduction such as propylene and other C4-C6 products could be formed.

Green Synthesis of 3-Hydroxybutyraldehyde from Acetaldehyde Catalyzed by La-Ca-Modified MgO/Al2O3

3-hydroxybutyraldehyde (3-HBA) is mainly employed to synthesize 1,3-BDO (1,3-butanediol), which is one of the most important components in cosmetics moisturizers. In this study, a series of composite oxide catalysts were prepared by bringing alkaline earth metal Ca and rare earth metal La to the composite oxide MgO/Al2O3, which were made through the co-precipitation method. These catalysts were applied in the synthesis of 3-HBA through acetaldehyde (AcH) condensation. The structure, texture, and acidic properties of these catalysts were characterized using various characterization methods, and the effects of catalyst composition, reaction temperature, reaction pressure, and residence time on the conversion of AcH were investigated as well. The results showed that the introduction of Ca and La weakened the acidic property and enhanced the basic property, which favored the AcH condensation to synthesize 3-HBA. At a temperature of 20 °C, pressure of 200 kPa, and residence time of 70 min, 0.5%La-2.3%Ca-2MgO/Al2O3 exhibited a better catalytic activity, and the conversion of AcH reached 95.89%. The selectivity and yield of 3-HBA were 92.08% and 88.30%, respectively. The stability test indicated that the high AcH conversion could be maintained for 5 h.

In Vitro One-Pot 3-Hydroxypropanal Production from Cheap C1 and C2 Compounds.

One- or two-carbon (C1 or C2) compounds have been considered attractive substrates because they are inexpensive and abundant. Methanol and ethanol are representative C1 and C2 compounds, which can be used as bio-renewable platform feedstocks for the biotechnological production of value-added natural chemicals. Methanol-derived formaldehyde and ethanol-derived acetaldehyde can be converted to 3-hydroxypropanal (3-HPA) via aldol condensation. 3-HPA is used in food preservation and as a precursor for 3-hydroxypropionic acid and 1,3-propanediol that are starting materials for manufacturing biocompatible plastic and polytrimethylene terephthalate. In this study, 3-HPA was biosynthesized from formaldehyde and acetaldehyde using deoxyribose-5-phosphate aldolase from Thermotoga maritima (DERATma) and cloned and expressed in Escherichia coli for 3-HPA production. Under optimum conditions, DERATma produced 7 mM 3-HPA from 25 mM substrate (formaldehyde and acetaldehyde) for 60 min with 520 mg/L/h productivity. To demonstrate the one-pot 3-HPA production from methanol and ethanol, we used methanol dehydrogenase from Lysinibacillus xylanilyticus (MDHLx) and DERATma. One-pot 3-HPA production via aldol condensation of formaldehyde and acetaldehyde from methanol and ethanol, respectively, was investigated under optimized reaction conditions. This is the first report on 3-HPA production from inexpensive alcohol substrates (methanol and ethanol) by cascade reaction using DERATma and MDHLx.

Supported molybdenum oxides for the aldol condensation reaction of acetaldehyde

The (retro-)aldol condensation reaction is an important chemical transformation in the upgrading of biomass-derived compounds into fuels and valuable specialty chemicals. In this study, we found that supported molybdenum oxide (MoOx) catalysts were active and selective for the aldol condensation of acetaldehyde to crotonaldehyde under steady-state reactor conditions. Through a combination of transmission electron microscopy (TEM), ultraviolet–visible (UV–VIS) diffuse reflectance spectroscopy, Fourier transform infrared (FTIR) spectroscopy of adsorbed pyridine, and steady-state reactor testing, we determined that highly dispersed MoOx has a strong interaction with a γ-Al2O3 support resulting in optimal catalyst performance at low weight loadings. In contrast, MoOx particles supported on SiO2 have a weaker interaction with the support, resulting in a monotonic relationship between Mo loading and aldol condensation activity. The Lewis acid site density and strength are important parameters for predicting aldol condensation activity across all samples. The concentration of weak acid sites had a poor correlation with aldol condensation activity, most likely because these sites are too weak to activate acetaldehyde for the reaction. Medium and strong acid sites both had good correlations to aldol condensation activity. Results from X-ray absorption near edge structure (XANES) and acetaldehyde temperature programmed desorption (TPD) indicated that partially reduced MoOx was more active for aldol condensation, but pretreatment in reducing or oxidizing environments had no significant effect on steady-state catalytic activity. Characterization of spent catalyst samples through temperature programmed oxidation (TPO) and thermogravimetric analysis (TGA) revealed that catalysts with high densities of strong acid sites tended to form more carbonaceous deposits on the surface over the course of the reaction.

Atomic Ru catalysis for ethanol coupling to C4+ alcohols

Transformation of ethanol to more valuable C4+ alcohols by coupling reaction has been of great interest from the point of view of chemistry and technology of biomass utilization. This work reports atomic Ru on Mg and Al containing layered double oxides (MgAl-LDO) for ethanol coupling to C4+ alcohols. The atomic Ru remarkably promotes the coupling of ethanol, achieving a selectivity of 82.6% to C4+ alcohols under an ethanol conversion of 29.6%. Through tailoring Ru dispersion and acid-base properties, it has been found that atomic Ru promotes ethanol dehydrogenation and the following aldol condensation of acetaldehyde.

Investigating the role of metals loaded on nitrogen-doped carbon-nanotube electrodes in electroenzymatic alcohol dehydrogenation

A new enzymatic biofuel cell (EBFC) is developed using conductive metal alloy nanoparticles with carbon cloth (CC) as an immobilization support for ethanol dehydrogenase (EtDH) and formolase (FLS). Ethanol (EtOH) dehydrogenation to acetaldehyde via direct electron transfer (DET) is pursued as the first step, followed by the condensation of acetaldehyde to acetoin. Metals are deposited onto novel three-dimensional jellyfish (JF)-shaped nanoparticles (SiO2–NCNT–CoFe2), where NCNT denotes “N-doped carbon nanotube”. The fabricated JF–metal–CC–EtDH bioelectrodes exhibit a variation in power generation with varying metals, with a value 37.6-fold higher than that of previously reported EBFC operations with DET for EtOH oxidation. The highest acetoin content is also found in JF-Os–CC–EtDH–FLS, attributable to faster electron uptake by the bioelectrode. First-principles calculations suggest that the d-state delocalization of metal-loaded JF particles is the cause of the enhanced catalytic activity, and it can be utilized in designing electrocatalysts.

Synthesis of 3-hydroxybutyraldehyde over highly stable solid base catalysts prepared from layered double hydroxides

3-Hydroxybutyraldehyde (3-HBA) is an important intermediate for the manufacture of biodegradable plastics (polyhydroxyalkanoate), and it is of great significance to find an efficient way for the catalytic synthesis of 3-HBA from surplus acetaldehyde. In this work, a series of MgxAlO(x+1.5)-t (t referred to the calcination temperature) solid bases were prepared via the controlled calcination of MgxAl layered double hydroxides with different ratio of Mg/Al and tested in the aldol condensation of acetaldehyde to 3-HBA. Characterization results revealed that the formed MgO particles were embedded in magnesium aluminate spinel (MgAl2O4) in Mg3AlO4.5–1100, which exhibited excellent activity and stability in the continuous liquid flow condensation of acetaldehyde. The detected selectivity of 3-HBA reached 89.0% with a 73.8% conversion of acetaldehyde at 25 °C and WHSV−1 = 2.8 h. Meantime, Mg3AlO4.5–1100 catalyst could retain its activity within 300 h on stream. What's more, the reaction mechanism over Mg3AlO4.5–1100 catalyst was proposed according to the results of several experiments.

Mechanistic Insights into the Selective Electroreduction of Crotonaldehyde to Crotyl Alcohol and 1-Butanol.

The electroreduction of crotonaldehyde, which can be derived from the aldol condensation of acetaldehyde (sustainably produced from CO2 reduction or from biomass ethanol), is potentially a carbon-neutral route for generating high-value C4 chemicals such as crotyl alcohol and 1-butanol. Developing functional catalysts is necessary toward this end. Herein, the electrocatalytic conversion of crotonaldehyde to crotyl alcohol and 1-butanol was achieved in 0.1 m potassium phosphate buffer electrolyte (pH=7). More importantly, the mechanisms and structure-activity relationships of these transformations were elucidated. Crotyl alcohol was formed on oxide-derived Ag at -0.75 V versus the reversible hydrogen electrode (RHE) with a faradaic efficiency (FE) of 84.3 % (reactant conversion after 75 min electrolysis=9.8 %), which is 1.6 times higher than that on polished Ag foils. The coordinatively-unsaturated sites on oxide-derived Ag surfaces were proposed to facilitate crotonaldehyde adsorption via its oxygen atom in order to promote crotyl alcohol formation. On electrodeposited Fe nanoflakes, crotonaldehyde could be reduced to 1-butanol with an outstanding FE of 60.6 % (reactant conversion after 75 min electrolysis=9.4 %) at -0.70 V vs. RHE. This is nearly 3 times higher than the FE of 1-butanol observed on polished Fe foils at the same potential. More strikingly, the corresponding partial current density of 1-butanol was -9.19 mA cm-2 , which is 43 times higher than that on Fe foils. The presence of tensile strains and grain boundaries on the Fe nanoflakes were elucidated and suggested to activate a concerted reduction of the C=O and C=C bonds in crotonaldehyde to produce 1-butanol selectively.

Rational design to enhance the catalytic activity of 2-deoxy-D-ribose-5-phosphate aldolase from Pseudomonas syringae pv. syringae B728a

The 2-Deoxy-d-ribose-5-phosphate aldolase (DERA) enzyme in psychrophilic bacteria has gradually attracted the attention of researchers. A novel gene, deoC (681 bp), encoding DERAPsy, was identified in Pseudomonas syringae pv. syringae B728a, recombinantly expressed in E. coli BL21 and purified via affinity chromatography, which yielded a homodimeric enzyme of 23 kDa. The specific activity of DERAPsy toward 2-deoxy-d-ribose-5-phosphate (DR5P) was 7.37 ± 0.03 U/mg, and 61.32% of its initial activity remained after incubation in 300 mM acetaldehyde at 25 °C for 2 h. Based on the calculation results (dock binding free energy) with the ligand chloroacetaldehyde (CAH), five target substitutions (T16L, F69R, V66K, S188V, and G189R) were identified, in which the DERAPsy mutant (G189R) exhibited higher catalytic activity toward DR5P than DERAPsy. Only the DERAPsy mutant (V66K) exhibited 12% higher activity toward chloroacetaldehyde and acetaldehyde condensation reactions than DERAPsy. Fortunately, the aldehyde tolerance of these mutants exhibited no significant decline compared with the wild type. These results indicate an effective strategy for enhancing DERA activity.

Fixed-Bed Reactor with Side Injection: A Promising Option for the Aldol Condensation of Acetaldehyde

The aldol condensation of acetaldehyde with other carbonyl molecules is a complex reaction wherein there is often formation of multiple undesirable side products. These side products include higher...

Role of Lewis Acids of MIL-101(Cr) in the Upgrading of Ethanol to n-Butanol

The upgrading of bioethanol to n-butanol has recently been a focus of considerable attention due to the advantages of n-butanol over bioethanol as a sustainable fuel. The efficiency of this reaction is highly dependent on the development of catalysts, where understanding how catalysts perform is essential. However, traditional catalysts are normally composed of several kinds of active sites that work together synergistically in reactions, making it challenging to identify the role that individual active sites play. Herein, we synthesized three chromium-based MOFs ((MIL-101(Cr), where MIL stands for Matériaux Institut Lavoisier) with different Lewis acidities but without any basic sites. The linear relationship between Lewis acidities and their dehydration and condensation abilities suggests that there is a competition between the ethanol dehydration to diethyl ether and acetaldehyde condensation on Lewis acids. Upon the introduction of Pd, the Lewis acidity also dominates the particle size of Pd and then the dehydrogenation and hydrogenating abilities of catalysts.