Conversion Of Glycol Research Articles

Quest for pore size effect on the catalytic property of defect-engineered MOF-808-SO4 in the addition reaction of isobutylene with ethylene glycol

In this article, we use defect engineering approach to fine-tune the pore size of MOF-808-SO4. A series of defective MOF-808-SO4 with different pore size were prepared by varying the amount of isophthalic acid as the defective ligand during the synthesis. We obtained a linear correlation between the concentration of the defective ligand and the pore size via regression analysis. The pore size exerts a significant effect on the catalytic activity in the addition reaction of isobutylene with ethylene glycol. The highest conversion of ethylene glycol was found over MOF-808-20%-SO4 (2.25 nm) with the largest pore size, whereas MOF-808-5%-SO4 (1.46 nm) and MOF-808-10%-SO4 (1.53 nm) exhibited higher selectivity toward ethylene glycol mono-tert-butyl ether. There is a linear correlation between the pore size and catalytic activity only when the pore size ranges from 1.4 to 2.0 nm. MOF-808-15%-SO4 with the pore size of 1.99 nm exhibits the highest yield of ethylene glycol mono-tert-butyl ether.

Specific Inhibition of Hepatic Lactate Dehydrogenase Reduces Oxalate Production in Mouse Models of Primary Hyperoxaluria.

Primary hyperoxalurias (PHs) are autosomal recessive disorders caused by the overproduction of oxalate leading to calcium oxalate precipitation in the kidney and eventually to end-stage renal disease. One promising strategy to treat PHs is to reduce the hepatic production of oxalate through substrate reduction therapy by inhibiting liver-specific glycolate oxidase (GO), which controls the conversion of glycolate to glyoxylate, the proposed main precursor to oxalate. Alternatively, diminishing the amount of hepatic lactate dehydrogenase (LDH) expression, the proposed key enzyme responsible for converting glyoxylate to oxalate, should directly prevent the accumulation of oxalate in PH patients. Using RNAi, we provide the first in vivo evidence in mammals to support LDH as the key enzyme responsible for converting glyoxylate to oxalate. In addition, we demonstrate that reduction of hepatic LDH achieves efficient oxalate reduction and prevents calcium oxalate crystal deposition in genetically engineered mouse models of PH types 1 (PH1) and 2 (PH2), as well as in chemically induced PH mouse models. Repression of hepatic LDH in mice did not cause any acute elevation of circulating liver enzymes, lactate acidosis, or exertional myopathy, suggesting further evaluation of liver-specific inhibition of LDH as a potential approach for treating PH1 and PH2 is warranted.

Engineering Pseudomonas putida KT2440 for efficient ethylene glycol utilization

Ethylene glycol is used as a raw material in the production of polyethylene terephthalate, in antifreeze, as a gas hydrate inhibitor in pipelines, and for many other industrial applications. It is metabolized by aerobic microbial processes via the highly toxic intermediates glycolaldehyde and glycolate through C2 metabolic pathways. Pseudomonas putida KT2440, which has been engineered for environmental remediation applications given its high toxicity tolerance and broad substrate specificity, is not able to efficiently metabolize ethylene glycol, despite harboring putative genes for this purpose. To further expand the metabolic portfolio of P. putida, we elucidated the metabolic pathway to enable ethylene glycol via systematic overexpression of glyoxylate carboligase (gcl) in combination with other genes. Quantitative reverse transcription polymerase chain reaction demonstrated that all of the four genes in genomic proximity to gcl (hyi, glxR, ttuD, and pykF) are transcribed as an operon. Where the expression of only two genes (gcl and glxR) resulted in growth in ethylene glycol, improved growth and ethylene glycol utilization were observed when the entire gcl operon was expressed. Both glycolaldehyde and glyoxal inhibit growth in concentrations of ethylene glycol above 50 mM. To overcome this bottleneck, the additional overexpression of the glycolate oxidase (glcDEF) operon removes the glycolate bottleneck and minimizes the production of these toxic intermediates, permitting growth in up to 2 M (~124 g/L) and complete consumption of 0.5 M (31 g/L) ethylene glycol in shake flask experiments. In addition, the engineered strain enables conversion of ethylene glycol to medium-chain-length polyhydroxyalkanoates (mcl-PHAs). Overall, this study provides a robust P. putida KT2440 strain for ethylene glycol consumption, which will serve as a foundational strain for further biocatalyst development for applications in the remediation of waste polyester plastics and biomass-derived wastewater streams.

Metabolic engineering of Escherichia coli for the production of L-malate from xylose

Malate is regarded as one of the key building block chemicals which can potentially be produced from biomass at a large scale. Although glucose has been extensively studied as the substrate for malate production, its high price and potential competition with food production are serious limiting factors. In this study, Escherichia coli was metabolically engineered to effectively produce malate from xylose, the second most abundant sugar component of lignocellulosic biomass. First, the biosynthetic route of malate was constructed by overexpressing D-tagatose 3-epimerase, L-fuculokinase, L-fuculose-phosphate aldolase, and aldehyde dehydrogenase A. Second, genes encoding malic enzyme, malate dehydrogenase, and fumarate hydratase were knocked out to eliminate malate consumption, resulting in a titer of 1.99 g/l malate and a yield of 0.47 g malate/g xylose. Third, glycolate oxidase and malate synthase were overexpressed to strengthen the conversion of glycolate to malate, which led to a titer of 4.33 g/l malate and a yield of 0.83 g malate/g xylose, reaching 93% of the theoretical yield. Finally, catalase HPII was overexpressed to decompose H2O2 and alleviate its toxicity, which improved cell growth and further boosted malate titer to 5.90 g/l with a yield of 0.80 g malate/g xylose. To the best of our knowledge, this is the first study to report efficient malate production from xylose as the carbon source.

Renewable hydrogen production by ethylene glycol steam reforming over Al2O3 supported Ni-Pt bimetallic nano-catalysts

Abstract The steam reforming of ethylene glycol, a simple model compound for biomass-derived liquids, is considered to be an environmentally green process for producing renewable hydrogen. Both Pt and Ni species are known for their catalytic activity under steam reforming reaction conditions. In this investigation, alumina supported Ni-Pt bimetallic catalysts (X wt% Ni-Y wt% Pt/Al2O3 named XNi-YPt) were employed for steam reforming of ethylene glycol. The prepared catalysts were characterized by XRD, BET, H2-TPR, H₂-Chemisorption, and TEM. It was observed that Ni/Pt ratio strongly affected the redox behavior, BET surface area, and particle size of the samples that in turn affected their catalytic performance. The optimum catalyst sample was 3.75Ni-1.25 Pt which resulted in the highest ethylene glycol conversion (60%), highest H2 selectivity (45%) and yield (27%), and a minimum of 20 h of stability due to the lowest amount of coke formed the catalyst surface. The overall order of the catalytic performance of the samples was as follows: 3.75Ni-1.25 Pt > 2.5Ni-2.5 Pt > 1.25Ni-3.75 Pt > 0Ni-5Pt > 5Ni-0Pt. A kinetic model for the steam reforming of ethylene glycol in a packed bed reactor containing the 3.75Ni-1.25 Pt catalyst was employed indicating a good agreement between experimental and predicted H2 selectivity and yield. Intrinsic reaction rate data in the absence of the heat and mass transfer limitations were obtained in parametric studies (Temperature range of 823–893 K, ethylene glycol mole fraction range of 0.056–0.116 and bed density of 18–26 kg m−3). Higher temperature and bed density and lower ethylene glycol mole fraction enhanced the reactivity. The maximum ethylene glycol conversion (70%), H2 yield (36.5%) and H2 selectivity (52%) was observed for conditions of 893 K, bed density of 24 kg m−3 and ethylene glycol mole fraction of 0.056.

Evaluation of a micro-channel reactor for steam reforming of ethylene glycol: A comparative study of catalytic activity of Pt or/and Ni supported γ-alumina catalysts

Steam reforming of ethylene glycol (EG) was studied using γ-alumina supported 12%Ni, 3%Pt and 3%Pt12%Ni catalysts, in a micro-channel reactor. The parallel micro-channels were etched on a stainless steel plate using micro-milling technique with high speed CNC machine. The catalysts were prepared by the incipient wetness impregnation method and were characterized by using XRD, BET, FE-SEM, H2-TPR and TGA analyses. The effects of reaction temperature and feed flow rate on the EG conversion, hydrogen yield and selectivities of the gaseous products were investigated. Experimental findings revealed that 3%Pt12%Ni/γ-alumina catalyst can provide the highest EG conversion (96.1%) with 76.6% hydrogen yield and 5.3% CO selectivity at 450 °C temperature and 4 mL h−1 feed flow rate. Furthermore, continuous EG steam reforming identified 3%Pt12%Ni/γ-alumina as the most stable catalyst. This catalyst can remain stable after being on stream for more than 20 h.

Ethylene glycol poisoning

Ethylene glycol poisoning

Etherification of different glycols with ethanol or 1-octanol catalyzed by acid zeolites

New routes for transforming biomass-derived glycols into value-added products through innovative catalytic processes are of great relevance in the chemical industry. The etherification of these glycols with alkyl alcohols is a process to produce oxygenated fuel additives, antimicrobial and antiseptic agents, and non-ionic surfactants. In this work, the etherification reaction of glycerol, 1,2-propylene glycol or ethylene glycol with ethanol or 1-octanol using USY, H-Beta and HZSM-5 zeolites as catalysts was investigated. The catalytic activity expressed as glycol conversion was correlated with the zeolite hydrophobicity index, that is, higher conversions were achieved with more hydrophobic zeolites. Considering glycol conversion and monoether distribution, HZSM-5 showed a good catalytic performance for the studied etherification reactions. The hydrophobicity/hydrophilicity of reactants and catalysts, and the framework structure of the zeolites are crucial properties for the catalytic behavior of the studied zeolites in the etherification reaction of glycols and alkyl alcohols.

Photocatalytic C[sbnd]C bond cleavage in ethylene glycol on TiO2: A molecular level picture and the effect of metal nanoparticles

Polyol conversion to value-added products is of great interest for the bio-diesel industry. Photocatalytic oxidation processes may offer a green approach for polyol conversion; however the lack of comprehensive mechanistic understanding from an interdisciplinary perspective limits or even misleads the design of highly selective and efficient photocatalysts for such process. Here we have studied the photocatalytic polyol conversion on pristine TiO2 and metal (Au, Pd, and Pt) nanoparticles (NPs) decorated TiO2 using ethylene glycol (EG) as the model compound. We have developed a mechanistic picture at molecular level by coupling in-situ surface science study on rutile (110) surface with in-situ vibrational-mass spectrometry study on TiO2 nanopowders. The CC bond cleavage was found to be the only pathway in EG photo-conversion under deaerated conditions, leading to the formation of formaldehyde and hydrogen. We rationalized that the desorption of the surface adsorbed H (Hads) to be the rate determining step (RDS), making pristine TiO2 a poor photocatalyst that only catalyze the EG conversion at very low surface coverages. The addition of metal NPs on TiO2 surface promotes the desorption of Hads significantly, thus leading to an enhanced CC bond cleavage performance at higher surface coverages that is more applicable.

Microwave-Assisted Synthesis of Ethylene Glycol-Intercalated NiAl LDHs and Their Application for Intracrystalline Catalytic Esterification with Naphthenic Acids in Crude Oil

Ethylene glycol (EG)-intercalated layered double hydroxides (LDHs) with various Ni/Al molar ratios were prepared by a microwave-assisted ion exchange method. In comparison with the conventional ion exchange method, this method can achieve a more ordered layered structure and reduce the ion exchange time from 12 h to 30 min. The as-prepared EG-intercalated LDHs were used as esterification catalysts to remove naphthenic acids in crude oil. It is found that EG-intercalated LDHs may act as nanosized intracrystalline catalytic microreactors, attributed to the preintercalated EG which reduces the diffusion resistance, the enlarged interlayer space which facilitates the access of naphthenic acids, and metal catalytic sites in the layer. The confined interlayer space enhances the collision between reactants and accelerates the reaction. Therefore, EG-intercalated LDHs exhibit several times higher acid removal ratio and EG conversion than nitrate LDHs. The increasing Ni/Al ratio increases the amount of catalytic s...

Photoelectrochemical Reduction of CO2 to Ethylene Glycol on IL-SAM-Modified Au Electrodes

As civilization continues to evolve, fossil resources are depleting and carbon dioxide (CO2) emissions are increasing. Recently, the conversion of CO2 to fuels has attracted much attention as one of the solution for resolving the above problems. Among them the conversion technologies powered by solar energy are expected to be clean methods, and some carbon compounds are generated with <10% conversion efficiencies. However, all these compounds have only one carbon atom, and compounds with a C-C bond have not been reported. Recently, our group found that the imidazolium ion-terminated self-assembled monolayer (IL-SAM)-modified electrodes promote electrochemical conversion of CO2 to ethylene glycol with high selectivity (the Faraday efficiency is >80%) in an aqueous electrolyte solution.[1] Here we report that the SAM-modified electrodes promote the solar energy conversion to ethylene glycol from CO2. The activity of photoelectrochemical CO2 reduction was investigated in a two-compartment cell with an anion exchange membrane. We utilized a two-wired photovoltaic (PV) cell system, wherein a four series-connected crystal silicon PV and platinum were used as the photoelectric conversion element and anode, respectively. The cathode was synthesized by a similar method as described previously.[1] The reaction was performed by irradiation of simulated solar light, and the light intensity and the acceptance surface area of the PV were regulated so as to keep the applied potential of cathode at -0.58 V (v.s. RHE). Potassium bicarbonate dissolved in an aqueous solution was used as an electrolyte. During the reaction, CO2 was bubbled through the cathode solution, and the catholyte was periodically drawn into a syringe and directly analyzed by gas chromatography. Initially, a high reaction current was obtained due to the electrical double layer and other effects, but several minutes later the value became approximately constant. The production rate of ethylene glycol at 3 h was 1.8 μmol and solar-to-ethylene glycol conversion efficiency was 0.16%. In this reaction, CO2 initially interacted with the C-2 ring position of the electrochemically deprotonated imidazolium, and produced a carboxylate species. The adjacent two imidazolium carboxylate species formed a dimer followed by the generation of oxalate, leading to further reduction to ethylene glycol on the imidazolium catalysts of the SAM. From this research, we achieved the photoelectrochemical conversion of CO2 to ethylene glycol with a C-C bond structure.[1] J. Tamura, A. Ono, Y. Sugano, C. Huang, H. Nishizawa, S. Mikoshiba, Phys. Chem. Chem. Phys. 2015, 17, 26072.

Inhibition of Glycolate Oxidase With Dicer-substrate siRNA Reduces Calcium Oxalate Deposition in a Mouse Model of Primary Hyperoxaluria Type 1

Primary hyperoxaluria type 1 (PH1) is an autosomal recessive, metabolic disorder caused by mutations of alanine-glyoxylate aminotransferase (AGT), a key hepatic enzyme in the detoxification of glyoxylate arising from multiple normal metabolic pathways to glycine. Accumulation of glyoxylate, a precursor of oxalate, leads to the overproduction of oxalate in the liver, which accumulates to high levels in kidneys and urine. Crystalization of calcium oxalate (CaOx) in the kidney ultimately results in renal failure. Currently, the only treatment effective in reduction of oxalate production in patients who do not respond to high-dose vitamin B6 therapy is a combined liver/kidney transplant. We explored an alternative approach to prevent glyoxylate production using Dicer-substrate small interfering RNAs (DsiRNAs) targeting hydroxyacid oxidase 1 (HAO1) mRNA which encodes glycolate oxidase (GO), to reduce the hepatic conversion of glycolate to glyoxylate. This approach efficiently reduces GO mRNA and protein in the livers of mice and nonhuman primates. Reduction of hepatic GO leads to normalization of urine oxalate levels and reduces CaOx deposition in a preclinical mouse model of PH1. Our results support the use of DsiRNA to reduce liver GO levels as a potential therapeutic approach to treat PH1.

Photorespiratory glycolate oxidase is essential for the survival of the red alga Cyanidioschyzon merolae under ambient CO2 conditions.

Photorespiration is essential for all organisms performing oxygenic photosynthesis. The evolution of photorespiratory metabolism began among cyanobacteria and led to a highly compartmented pathway in plants. A molecular understanding of photorespiration in eukaryotic algae, such as glaucophytes, rhodophytes, and chlorophytes, is essential to unravel the evolution of this pathway. However, mechanistic detail of the photorespiratory pathway in red algae is scarce. The unicellular red alga Cyanidioschyzon merolae represents a model for the red lineage. Its genome is fully sequenced, and tools for targeted gene engineering are available. To study the function and importance of photorespiration in red algae, we chose glycolate oxidase (GOX) as the target. GOX catalyses the conversion of glycolate into glyoxylate, while hydrogen peroxide is generated as a side-product. The function of the candidate GOX from C. merolae was verified by the fact that recombinant GOX preferred glycolate over L-lactate as a substrate. Yellow fluorescent protein-GOX fusion proteins showed that GOX is targeted to peroxisomes in C. merolae The GOX knockout mutant lines showed a high-carbon-requiring phenotype with decreased growth and reduced photosynthetic activity compared to the wild type under ambient air conditions. Metabolite analyses revealed glycolate and glycine accumulation in the mutant cells after a shift from high CO2 conditions to ambient air. In summary, or results demonstrate that photorespiratory metabolism is essential for red algae. The use of a peroxisomal GOX points to a high photorespiratory flux as an ancestral feature of all photosynthetic eukaryotes.

Study on the esterification for ethylene glycol diacetate using supported ionic liquids as catalyst: Catalysts preparation, characterization, and reaction kinetics, process

Three supported ionic liquids (SILs) were synthesized and characterized. And the catalytic activity for the preparation of ethylene glycol diacetate (EGDA) via the esterification of ethylene glycol (EG) and acetic acid were studied. Among them, [Silica-Ps-im]HSO4 performed best and was chosen as catalyst for further study. The reaction kinetics experiments were carried out to correlate the parameters in a pseudo-homogeneous second order kinetic model. It has been found that there is good agreement between the calculated values and experimental data. In order to enhance the conversion of EG and yield of EGDA, a batch reactive distillation experimental apparatus was set up. A high conversion of EG of 100% and yield of EGDA of 99.14% were obtained under the optimal reaction conditions. The reusability test shows that [Silica-Ps-im]HSO4 catalyst has excellent utility for repeated use, the ease of its isolation from reaction mixture by simple filtration is beneficial from an economical point of view.

Hydrogen production from steam reforming of ethylene glycol over supported nickel catalysts

A series of nickel catalysts were prepared by the impregnation and co-precipitation methods and characterized by X-ray diffraction, nitrogen physisorption, and H2 temperature-programmed reduction. The effects of nickel loading, calcination temperature, reaction temperature, support modification and cobalt oxide addition on the catalytic activity and selectivity to H2 in the steam reforming of ethylene glycol were investigated. The results indicate that the nickel catalyst prepared by co-precipitation has smaller particle size and relatively higher activity in comparison with the catalyst prepared by impregnation. Adding a small amount of cobalt oxide to the Ni/CeO2 catalysts can enhance the catalytic activity; over the Ni-Co bimetallic catalyst, the yield of hydrogen reaches 72.6%. Modifying CeO2 with Al2O3, TiO2 and ZrO2 also has a certain influence on the catalytic activity and the Ni/CeO2-Al2O3 catalyst exhibits the highest activity, with an ethylene glycol conversion of 94% to gaseous products and a hydrogen yield of 67%. However, Ni/CeO2-SiO2 shows a very low activity in spite of its large surface area and pore volume.

Hydrogen production by aqueous-phase reforming of ethylene glycol over a Ni/Zn/Al derived hydrotalcite catalyst

The article presented the aqueous-phase reforming of ethylene glycol over Ni/Zn/Al hydrotalcite. The results showed that the H2 yield and selectivity were 73% and 96%, respectively. The conversion of ethylene glycol was &gt;99%.

ROS production is associated with glycolate metabolism in Chlamydomonas reinhardtii (Chlorophyceae) under salt stress

:The photorespiration metabolism in unicellular algae is different from that in higher plants because of the absence of peroxisomes, and conversion of glycolate to glyoxylate is catalyzed by glycolate dehydrogenase without the production of reactive oxygen species (ROS). It has been reported that the glycolate–quinone oxidoreductase system (GQOS) also plays a role in the formation of glyoxylate from glycolate that is coupled to photosynthetic electron transport. In this study, we showed that production of ROS was associated with the oxidation of glycolate in chloroplasts of Chlamydomonas reinhardtii cells and that both ROS accumulation and photorespiration were promoted by NaCl stress. Salicylhydroxamic acid (SHAM) and methoxylamine (MOA) are inhibitors that block effectively the GQOS oxidation of glycolate and glycine decarboxylase complex, respectively. Our data showed that in the dark, whether or not the cells were treated with inhibitor, no remarkable difference was found in ROS levels under the same NaCl stress. In the light, however, the ROS level in the cells treated with SHAM or MOA was significantly lower than that in nontreated cells, with SHAM being more effective. The increase in serine:glyoxylate aminotransferase (SGAT) activity and glycine/serine (Gly/Ser) ratio were 8.3% and 30.8% under 50 mM, and reached 34.4% and 1.5-fold under 100 mM NaCl stress.

On the Efficacy of Ru/Al2O3 Catalyst for Steam Reforming of Ethylene Glycol

This work describes hydrogen (H2) production via steam reforming of ethylene glycol (EG) over a supported ruthenium catalyst. EG is chosen as a model compound for the alcohols contained in the aqueous phase of bio-oil. Using a fixed-bed reactor, experimental runs are carried out over Ru/Al2O3 at various temperatures (350–500°C), ratios of the mass of the catalyst (W) to the molar flow rate (FO) of EG at the inlet (W/FO = 0.37 − 2.38 g h/mol), and feed concentrations (22.3–53.4 wt.% EG in water). The role of Ru in conversion of EG, production of H2, and product distribution of the carbonaceous species is studied. Reaction pathways previously described in the literature are used to elucidate our results.

Synthesis of long alkyl chain ethers through etherification of ethylene glycol with 1-octene using heteropolyacid supported on K-10 clay

Transesterification of vegetable oil with lower alcohols leads to biodiesel formation which is accompanied by ∼10wt% glycerol as the co-product. Since biodiesel production is going on massive scale across the world, huge quantity of surplus glycerol will be available. Bioglycerol ought to be converted into valuable chemicals and fuels to enable biodiesel to be cost competitive with reference to petro-diesel. Depending on reaction conditions and catalysts, the hydrogenolysis/hydrogenation of glycerol can produce 1,2-propylene glycol, 1,3-propylene glycol, and ethylene glycol; all of which can be further converted into valuable chemicals. The objective of the current work was to convert ethylene glycol to value added etherified products by reaction with 1-octene to 2-(octan-2-yloxy) ethanol (C8 ether) and 1,2-bis(octan-2-yloxy) ethane (C16 ether). Several heterogeneous solid acid catalysts were used such as 20% (w/w) dodecatungstophosphoric acid (DTP) supported on K10 clay (DTP/K10), 20% (w/w) Cs2.5H0.5PW12O40/K10 (Cs-DTP/K10), 20% (w/w) DTP/ZrO2, and Amberlyst-35. Among them 20% (w/w) DTP/K10 was found to be the most efficient catalyst with 72% conversion of ethylene glycol and 80% of selectivity toward 2-(octan-2-yloxy) ethanol (C8 ether). The optimum reaction conditions were as follows: ethylene glycol to 1-octene mole ratio 1:3, catalyst loading 0.03g/cm3, temperature 140°C, pressure 1.5MPa, reaction time 5h. The effects of different process parameters such as speed of agitation, catalyst loading, mole ratio, temperature, and reusability of the catalyst were studied to examine the efficacy of 20% (w/w) DTP/K10. The process is solvent less, green and clean. Other substrates were also used to enhance the scope of this work.

Sustainable syngas production from ethylene glycol reforming processes using Rh-based catalysts in microreactors

In this work the ethylene glycol (EG) as feed for syngas production by steam reforming (SR) and oxidative steam reforming (OSR) was studied applying microchannel testing reactors. The product composition was determined at a steam to carbon ratio (S/C) of 4.0, reaction temperatures between 625°C and 725°C and atmospheric pressure at volume hourly space velocities (VHSV) of the feed between 100 and 300NL/(gcath). Catalysts with different rhodium loading were prepared by two different preparation methods (conventional impregnation and separate nanoparticle synthesis) and compared with regard to their activity and selectivity. All the catalysts were characterized using the following techniques: N2 physisorption, temperature programmed reduction (TPR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Under all experimental conditions full conversion of ethylene glycol was achieved over the samples containing 2.5% and 5% Rh prepared by the impregnation method, equilibrium selectivity towards CO and CO2, lowest selectivity towards CH4 and lowest formation of by-products such as CH3CHO and C2 hydrocarbons. The other catalysts showed lower activity. The superior performance of the catalysts prepared by the impregnation method is supported by the measured higher rhodium dispersion of these samples.