Copper Chromium Oxide Catalyst Research Articles

The Ammonia Leaching Method of Recycling the Spent Copper-Chromium Oxide Catalysts

The spent copper chromium oxide catalyst of furfural hydrogenation was recycled.by ammonia leaching method. This method not only has the characteristics of simple process, low cost, quick effect, but also avoids the use of various oxidants increasing the security of the experimental operation and the generation of carcinogen hexavalent chromium.The experimental results show that the optimum process conditions of ammonia leaching is: the concentration of ammonia 15mol / L, the leaching temperature is at 180 °C, leaching time for 4h, the optimal dosage of (NH4)2SO40.6g/10g. The copper leaching rate can reach more than 80% of the maximum.

Complete oxidation of ethanol, acetaldehyde and ethanol/methanol mixtures over copper oxide and copper-chromium oxide catalysts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComplete oxidation of ethanol, acetaldehyde and ethanol/methanol mixtures over copper oxide and copper-chromium oxide catalystsHariharan Rajesh and Umit S. OzkanCite this: Ind. Eng. Chem. Res. 1993, 32, 8, 1622–1630Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published inissue 1 August 1993https://doi.org/10.1021/ie00020a013RIGHTS & PERMISSIONSArticle Views1639Altmetric-Citations93LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts Get e-Alerts

In situ FT—IR study of copper—chromium oxide catalysts in CO oxidation

CO adsorption and CO oxidation by O 2 were studied over alumina-supported copper and copper—chromium oxide from 300 to 673 K. After evacuation at room temperature, Cu + CO and carbonate-like complexes were observed on copper-containing catalysts upon CO adsorption. Both the copper and the chromium oxide species were easier to reduce on CuO*Cr 2O 3/Al 2O 3 compared with CuO/Al 2O 3 and Cr 2O 3/Al 2O 3 owing to the presence of a mixed oxidic phase. CO can react directly from the gas phase with oxygen at the surface under formation of a CO 2 surface species as a reaction intermediate. This indicates an Eley—Rideal mechanism. CO 2 adsorption results in bands similar to those observed upon CO and upon CO and O 2 admission. CO 2 inhibits the CO oxidation reaction in two ways — via the more weakly, reversibly bound CO 2, and via the more strongly, irreversibly held carbonates.

Study of the competitive reactions between an α-β-unsaturated aldehyde and allylic alcohol on a copper chromite catalyst

It was previously shown that a copper chromium oxide catalyst (Cu/Cr=1) presents a good monohydrogenation selectivity towards conjugated dienes and a poor selectivity with α-unsaturated carbonyls. A study with a mixture citral-nerol at various hydrogen pressures allows to confirm that this is due to the reactivity of the intermediate allylic alcohol. At high pressure, the unsaturated alcohol competes with the initial reagent on the hydrogenation site; at low pressure, this competition decreases, but the allylic alcohol is isomerized on another active site.

The role of copper-chromium oxide catalysts in the thermal decomposition of ammonium perchlorate

The catalytic effects of doped or mixed CuO-Cr2O3 oxides on the thermal decomposition of ammonium perchlorate (AP) were investigated by using DTA, electrical conductivity and X-ray diffraction techniques. The results obtained revealed that the decrease in the defect electron of CuO catalyst doped with 1 at.% Cr3+ inhibited its activity, while the opposite effect was observed when Cr2O3 was doped with 1 at.% Cu2+. On increase of the concentrations of both oxides, the catalyst containing 70 at.% Cr3+ was found to be the most active during the decomposition of AP. The existence of CuCr2O4 at this ratio was demonstrated by X-ray diffraction. The activity of this spinel was explained on the basis of a hopping mechanism between Cr3+/Cr4+ active sites. Finally, the activation energies of different decomposition stages of AP alone and mixed with catalysts were calculated.

Study of copper-chromium oxide catalyst: Part IV. Thermal decomposition of basic copper(II)-ammine ammonium chromate

Abstract Basic copper(II)-ammine ammonium chromate (BCAAC) of the composition [(Cu 2+) 1+ x (NH 4 +) y (OH −) 2 2x+ y (NH 3) z (CrO 4 2−)] was prepared by the reaction of basic copper(II)-ammonium chromate (BCAC) with ammonia. Compounds with coefficients x, y, z varying in the approximate intervals 0 < x < 0.3, 0 < y < 0.2, 3 < z < 4 were obtained in dependence on p NH 3 . According to the results of IR, electronic and EPR spectra, NH 3 substitutes for oxygen and hydroxyl groups bound to Cu(II) and [Cu(NH 3) 4] 2+ complexcations are formed in BCAAC. This reaction is reversible at room temperature and it can be written schematically as [Display omitted] At 130° C and 180° C ammonia desorption takes place in the process of the thermal decomposition. At ca. 205 ° C an explosive Cr(VI) to Cr(III) reduction leads to copper-chromium oxide catalyst with highly disordered structure. After its heating to 500° C a system, which contains crystalline CuO and a metastable CuCr 2O 4 with a unit cell of orthorhombic symmetry ( a = 0.593 nm, b = 0.603 nm, c = 0.779 mn) was obtained. The activity of the catalyst in the hydrogenation-alkylation reaction is lower than the activity of the one prepared from BCAC at 270 °C.

Electron spin resonance study of the structural properties of copper–chromium oxide catalysts

Copper–chromium catalysts with spinel structure and containing different amounts of copper are shown to have residual ferrimagnetic behaviour at room temperature. The small super-exchange interactions, sensitively characterized by octahedral Cr3+ e.s.r. linewidth and magnetic susceptibility determination, are drastically modified by redox treatment and variation of the Cu/Cr ratio. Comparison with ESCA results leads these modifications to be assigned to octahedral Cu+ concentration changes, which are quantitatively determined. Existence of such copper sites, even in the presence of isoprene, which is hydrogenated to mono-olefin, suggests that octahedral Cu+ ions play an important role in the selective hydrogenation catalysis.

Reactions of nitrogen oxides (NO, N2O) with the surface of a copper-chromium oxide catalyst

Weight-space and IR spectroscopic methods have been used to investigate the reaction of NO and N2O with the surface of a copper-chromium oxide catalyst in the form of copper chromite with a 20% excess of Cr2O3. Comparisons have been made between the relative reactivities of the different oxides (NO, N2O, O2) in oxidation of the Cu+ and Cuo surface centers. The role of these centers in oxidation of CO by oxygen and by nitrogen oxides is discussed.

Reactivities of some carbonyl compounds of the furan series in catalytic hydrogenation

The rate of hydrogenation of some carbonyl compounds of the furan series on Raney nickel-titanium-aluminum and copper-chromium oxide catalysts decreased in proportion to the decrease in the frequency of the absorption band of the C=O bond.

1H-NMR study of hydrogen species in reduced copper-chromium oxide catalysts

1H-NMR study of hydrogen species in reduced copper-chromium oxide catalysts

Catalytic oxidation of carbon monoxide by oxygen and nitrogen oxides on a copper-chromium oxide catalyst

The kinetics of CO oxidation by O2, NO and NO2 has been studied on a Cu−Cr-oxide catalyst. A comparison with the kinetics of the CO−N2O interaction has been made. In all cases the reaction rate is described by the equation:r=k p CO 1 P 0x 0 . The oxidation of CO has been studied in the presence of different oxidants in the reaction mixture.

EVALUATION OF MASS TRANSFER EFFECTS ON CONSECUTIVE CATALYTIC REACTION USING AN INTERNAL-RECYCLE CATALYTIC REACTOR

An internal-recycle catalytic reactor is described which can be operated under perfectly mixed conditions. The reactor is suitable for evaluating intraparticle mass transfer effects on reaction rate and yield in the consecutive hydrogenation of mesityl oxide over a copper-chromium oxide catalyst. The reactor has the advantages that accurate reaction rates are directly obtained, and that mathematical formulation is simpler than with an integral reactor. Effective diffusivities are determined from conversion data and compared with those calculated by a parallel-pore model and a random-pore model. The effective diffusivities predicted by both models closely agree with each other, and these values are close to those experimentally determined. The tortuosity factors determined from the parallel-pore model range from 1.4 to 3.4. These values fall within the range of previously published values. The calculated conversion and yield show relatively good agreement with the experimental results.

Study on selective hydrogenation of ethyl ester of unsaturated fatty acids over copper-chromium oxide-catalyst and the rate influenced by various reaction conditions under high pressures

Selectivity between linoleic and oleic acids in pressurized hydrogenation with copperchromium oxide catalyst was found to be satisfactory, though oleic acid is saturated in a small rate at 180°. Several factors involved were examined at constant pressures to obtain an overall view. Pressure effect was of approximately Freundlich type, zero-order kinetics with respect to concentration of linoleic acid is held still under 40 kg/cm2, with activation energy of 15 kcal/mole averaged for 1 and 40 kg/cm2 hydrogenations, while an upper limitation to hydrogenation rate with increase in the amount of catalyst was less acute than was found at one atmospheric pressure, and stirring effect was markedly lowered as pressure rose.

Reaction between n-Octanol and Diethylamine

Authors investigated the reaction of n-octanol with diethyl amine as a model synthetic experiment of higher amine by the reaction between higher alcohol and lower amine.In the case of copper-chromium oxide as a catalyst, the reaction proceeded at 200300°C for a short time and approx. 30 percent of octyl ethyl amine and 30 percent of octyl diethyl amine were obtained. The copper chromium oxide catalysts were reduced into metallic copper during the reaction.The exchange reaction of alkyl groups proceeded at a lower temperature than that of the dehydration reaction between alcohol and amine.In the case of the metallic copper powder as a catalyst, the higher reaction temperature was required than the case of copper chromium oxide catalyst.The amines obtained were, in every case, mixed amines and solitary tertiary amine could not be synthesized.

STUDIES ON ACTIVITIES OF COPPER CHROMIUM OXIDE CATALYST REDUCED IN OIL PHASE

STUDIES ON ACTIVITIES OF COPPER CHROMIUM OXIDE CATALYST REDUCED IN OIL PHASE

STUDIES ON DISCONTINUOUS POISONING OF COPPER CHROMIUM OXIDE CATALYST DURING FATTY OIL HYDROGENATION

STUDIES ON DISCONTINUOUS POISONING OF COPPER CHROMIUM OXIDE CATALYST DURING FATTY OIL HYDROGENATION

REACTION BETWEEN 1-HEXENE AND HYDROGEN AND DEUTERIUM ON COPPER—CHROMIUM OXIDE CATALYST

Reaction of hydrogen and deuterium with 1-hexene was investigated in a vapor phase, flow reactor on copper-chromium oxide catalyst at temperatures of from 50 to 150 deg . The catalyst was pre-treated with hydrogen at 325 deg , There are three primary reactions, hydrogenation, isomerization to trans- and cis- 2-hexene which appear in a ratio of about 10, and formation of isotopically exchanged 1-hexene. The last reaction is the fastest and, as shown by n.m.r., it involves almost exclusively exchange at carbon atom-2 to form 1-hexene-2-d. The activation energy for isomerization is about 5 kcal greater than that for hydrogenation. The rates of the two reactions are equal at about 90 deg . At 60 deg , presence of 1-hexene almost completely inhibits hydrogenation of 2-hexene but it does not inhibit isomerization of 2- to 3-hexene. The isotopic distribution pattern of the hexene formed at low conversions seems to result from the addition of two (H,D) atoms to a mixture of 1-hexene and 1-hexene-2-d formed by previous exchange. Thus, during the course of hydrogenation, there seems to be little tendency for reversion of diadsorbed hexane to monoadsorbed. Isotopic distribution patterns for trans-2-hexene are presented and difficulties in the application ofmore » the Horiuti- Polanyi mechanism to olefin isomerization and exchange are discussed.« less

A Study of Copper-Chromium Oxide Catalysts and a Method to Determine Catalytic Activities

AbstractAn extensive investigation of chemical composition, particle size, and surface area of copper-chromium oxide catalysts has been made. The two phases present in the activated material are copper oxide (CuO) and copper-chromium spinel (CuCr2O4). The crystallite size of the CuO phase (determined by X-ray diffraction line broadening) can be correlated with the catalytic activity measured on a CO-CO2 oxidation reaction. The catalytic activity of the oxide catalyst can be expressed as a function of the X-ray fluorescence intensity of the Cu Kα line even on changing the absolute copper concentration up to 3%. An attempt is made to explain this phenomenon by the heterogeneity effect caused by the difference in the linear absorption factors for the Cu Kα radiation in the system CuO-CuCr2O4.

HYDROGENOLYSIS OF CARBOHYDRATES: IX. FORMATION OF 2,6-ANHYDRO-β-D-FRUCTOFURANOSE AND ETHYL α- AND β-D-FRUCTOFURANOSIDE FROM SUCROSE

A compound formed during the hydrogenolysis of sucrose in ethanol or dioxane at 180 °C, in the presence of copper chromium oxide catalyst, has been characterized as 2,6-anhydro-β-D-fructofuranose (2,5-anhydro-α-D-fructopyranose), a new type of anhydro-ketose. Ethyl α- and β-D-fructofuranosides are also produced when the hydrogenolysis reaction is carried out in ethanol, and various derivatives of these anomeric ketosides have been prepared.

HYDROGENOLYSIS OF CARBOHYDRATES: V. ISOMERIZATION OF METHYL β-L-ARABOPYRANOSIDE

Treatment of methyl β-L-arabopyranoside under hydrogenolytic conditions with copper chromium oxide catalyst induces extensive isomerization. Products formed include glycosides of D-ribose, D-xylose, D-lyxose, and L-lyxose which together represent about an 80–90% conversion of starting material. Isolation of these compounds shows that carbons 2, 3, and 4 undergo isomerization, but no evidence has been obtained of anomerization. These findings possibly explain the formation of an optically inactive mixture of cis- and trans-tetrahydropyran-3,4-diol under slightly more drastic reaction conditions.