Copper Loading Research Articles

The Catalytic Activity of Carbon-Supported Cu(I)-Phosphine Complexes for the Microwave-Assisted Synthesis of 1,2,3-Triazoles

A set of Cu(I) complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo-[3.3.1]nonane (DAPTA) phosphine ligands viz. [CuX(κP-DAPTA)3] (1: X = Br; 2: X = I) and [Cu(μ-X)(κP-DAPTA)2]2 (3: X = Br; 4: X = I) were immobilized on activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on these materials after surface functionalization. The immobilized copper(I) complexes have shown favorable catalytic activity for the one-pot, microwave-assisted synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition reaction (CuAAC). The heterogenized systems with a copper loading of only 1.5–1.6% (w/w relative to carbon), established quantitative conversions after 15 min, at 80 °C, using 0.5 mol% of catalyst loading (relative to benzyl bromide). The most efficient supports concerning heterogenization were CNT treated with nitric acid and NaOH, and involving complexes 2 and 4 (in the same order, 2_CNT-ox-Na and 4_CNT-ox-Na). The immobilized catalysts can be recovered and recycled by simple workup and reused up to four consecutive cycles although with loss of activity.

Effects of Different Copper Species on the Combustion of Dichloromethane over Cu/HZSM-5 Zeolite Nanoporous Catalysts

This study compared the reaction behaviors of dichloromethane (DCM) catalytic combustion over Cu/HZSM-5 (H form of Zeolite Socony Mobil-5) nanoporous catalysts at different copper loadings. Among t...

Comparative characterization of glyoxal oxidase from Phanerochaete chrysosporium expressed at high levels in Pichia pastoris and Trichoderma reesei

In the secretome of Phanerochaete chrysosporium, a white-rot fungus serving as a model organism to elucidate lignocellulose deconstruction, the copper containing metalloprotein glyoxal oxidase (GLOX) is potentially involved in the crucial production of hydrogen peroxide to fuel and initiate oxidative biomass degradation by lignin-degrading peroxidases. Its ability to oxidize a variety of aldehydes and α-hydroxy carbonyls with the concomitant reduction of dioxygen to hydrogen peroxide has attracted attention for its application as green biocatalyst in different industrial fields.Here we report and compare two efficient processes for the heterologous production of GLOX from P. chrysosporium using the well-established methanolytic yeast Pichia pastoris and the filamentous fungus Trichoderma reesei as expression hosts with subsequent purification by anion exchange and hydrophobic interaction chromatography. Both processes were shown to be suitable for the production of the target protein at high levels. GLOX produced in T. reesei carries mainly Man5 glycosylation while the enzyme produced in P. pastoris exhibits the typical high-mannose type N-glycosylation. The enzyme expressed in P. pastoris showed slightly higher specific activities which correlates with the higher copper loading of 65.5 % compared to 51.9 % for the protein from T. reesei. The pH optimum for both recombinant proteins was 6.0, however, GLOX activity was found to be highly affected by different buffer species. Both enzymes showed very similar substrate affinities and turnover numbers with the highest catalytic efficiency observed for methylglyoxal. GLOX from both expression hosts is therefore a suitable enzyme for further mechanistic characterization and application studies.

Copper-impregnated on natural material as promising catalysts for the wet hydrogen peroxide catalytic oxidation of Methyl Green

Promising catalyst of cooper impregnated on natural material (CT) synthesized via wet impregnation method, in order to enhance the catalytic wet peroxide oxidation during the degradation of organic matter in a batch reactor under mild conditions. Three different percentages of copper metal (2.5, 5 and 7.5 %) incorporated into CT material which are referred as follows 2.5% Cu-CT, 5% Cu-CT and 7.5% Cu-CT were investigated in the oxidation catalytic of methyl green (MG) dye. The chemical composition, the morphology and the structure of raw CT and all prepared samples, were investigated by X-ray fluorescence, Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) to get a better understand concerning the catalytic activity behavior of Cu-CT catalyst. Different variable examined the catalytic activity of the samples obtained such as initial concentrations of dye, copper (Cu) loading, temperature and H 2 O 2 effect was investigated to enhance the MG conversion. CWPO experiments showed that 2.5% Cu-CT catalysts have the maximum catalytic activity during the degradation of MG dye. The presence of copper on CT support ameliorates the hydroxyl radicals in the reaction medium after the contact with H 2 O 2 thus enhanced the catalytic conversion of the CT pristine. The optimum conditions showing an important catalytic conversion of MG dye (95 %) at 2.5% of copper loading, 139.10 -3 mol.L -1 H 2 O 2, temperature of 40 °C and at pH 6.0 during 30 min as a reaction time.

Stepwise methane to methanol conversion: Effect of copper loading on the formation of active species in copper-exchanged mordenite

This work investigates the influences of Cu content, Si/Al ratio, and sample preparation method on the active Cu species in mordenite (MOR). The Cu/MOR prepared by multiple Cu-exchange procedures showed an optimum Cu/Al ratio for the formation of the most active species for methanol formation. XANES spectra indicated that isolated Cu+ species were formed after CH4 interaction and were re-oxidized under a flow of water steam. The Cu-MOR samples obtained by ion-exchange method presented well-dispersed CuO in the zeolite pores, while samples obtained by impregnation method presented segregated CuO and were inactive for CH4 activation. The methodology used for in situ UV–vis spectra analyses indicated that different Cu species were active for CH4 oxidation. Isolated Cu2+ species were not involved in CH4 activation at temperatures lower than 300 °C. The isolated Cu2+ species were partially hydrolyzed by O2 treatment and species like [CuOH]+ and [CuOx]n or polynuclear Cu2+-oxyhydroxide were formed. The formation of polynuclear species in substitution of di-copper would impact the specific activity with the Cu content and decrease the activity for methanol production.

Wastewater Contaminated with Hydrazine as Scavenger Agent for Hydrogen Production by Cu/Ti Nanostructures

Cu/Ti photocatalysts were prepared by the sol-gel process with different copper loadings (1.0, 2.5, and 5.0 wt.%) and then thermally treated at several calcination temperatures from 400 to 600 °C. The materials were characterized by X-ray diffraction (XRD), N2 physisorption, Scanning Electronic Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS), Ultraviolet-visible-Diffuse Reflection Spectroscopy, Ultraviolet-visible spectroscopy as a function of the temperature, (Temperature Programmed Reduction) TPR-chemisorption, XPS (X-ray Photoelectron Spectroscopy) and OH determination through DRIFTS (Diffuse reflectance infrared Fourier transform spectroscopy). The Cu/Ti photocatalysts were evaluated for the photocatalytic production of hydrogen using hydrazine as scavenging agent. Moreover, a detailed study of the Cu1+/Cu2+ ratio and the corresponding formation of copper oxide was carried out to understand the correlation between the copper species and the photocatalytic activity. Simultaneously, the OH groups on the TiO2 surface also show insights into the behavior of these materials during the photocatalytic reaction. Despite the low hydrazine concentration (20 mM), the 1.0 (wt.%) Cu/Ti 500 photocatalyst enhanced the hydrogen production three and two times more than photolysis and bare TiO2, respectively. The 1.0 Cu/Ti 500 photocatalyst displayed outstanding stability for at least three continuous cycles of 8 h each, preserving the hydrogen production. The novel ability shown in this work represents an alternative to reduce the hydrazine residues in wastewater to transform it into a hydrogen-producing energy source and must be extended to other reductive pollutants found in wastewater.

Preparation of CuO/HZSM-5 catalyst based on fly ash and its catalytic wet air oxidation of phenol, quinoline and indole

This work aims to use fly ash and the organic template of tetrapropyl ammonium bromide (TPABr) to synthesize the catalyst carrier of HZSM-5 and prepare the catalyst of CuO/HZSM-5 for catalytic wet air oxidation (CWAO) of phenol, quinoline and indole in aqueous solution. The carrier and the catalyst were characterized by x-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF) and Brunauer-Emmett-Teller (BET) tests and the results indicate HZSM-5 zeolite and CuO/HZSM-5 catalyst have been successfully synthesized. The specific surface area of catalysts with copper loading from 0 to 15% decreased from 310.1 m2 g−1 to 253.8 m2 g−1. The results of catalyst performance showed that the catalyst of CuO/HZSM-5 with copper loading of 10% has the best removal effect on the mixed aqueous solution containing phenol, quinoline and indole. When the total concentrations of phenol, quinoline and indole are 200 mg.l−1 (namely 120 mg phenol·l−1, 60 mg quinoline·l−1 and 20 mg indole·l−1), the catalyst with the copper loading of 10% can remove these organic matters with 100% efficiency after reaction for 4 h at 200 °C and the COD removal rate is more than 75%. Under the same experimental conditions, if the reaction temperature drops to 120 °C, the COD removal rate will rise to 86.2%. The CWAO experiments showed the optimum reaction temperature range for the Cu-10% catalyst is from 120 °C to 150 °C.

In situ X-ray absorption study of Cu species in Cu-CHA catalysts for NH3-SCR during temperature-programmed reduction in NO/NH3

Ammonia-mediated selective catalytic reduction (NH3-SCR) using Cu-exchanged chabazite zeolites as catalysts is one of the leading technologies for NOx removal from exhaust gases, with CuII/CuI redox cycles being the basis of the catalytic reaction. The amount of CuII ions reduced by NO/NH3 can be quantified by the consumption of NO during temperature-programmed reduction experiments (NO-TPR). In this article, we show the capabilities of in situ X-ray absorption near-edge spectroscopy (XANES), coupled with multivariate curve resolution (MCR) and principal component analysis (PCA) methods, in following CuII/CuI speciation during reduction in NO/NH3 after oxidation in NO/O2 at 50 °C on samples with different copper loading and pretreatment conditions. Our XANES results show that during the NO/NH3 ramp CuII ions are fully reduced to CuI in the 50–290 °C range. The number of species involved in the process, their XANES spectra and their concentration profiles as a function of the temperature were obtained by MCR and PCA. Mixed ligand ammonia solvated complexes [CuII(NH3)3(X)]+ (X = OH−/O− or NO3−) are present at the beginning of the experiment, and are transformed into mobile [CuI(NH3)2]+ complexes: these complexes lose an NH3 ligand and become framework-coordinated above 200 °C. In the process, multiple CuII/CuI reduction events are observed: the first one around 130 °C is identified with the reduction of [CuII(NH3)3(OH/O)]+ moieties, while the second one occurs around 220–240 °C and is associated with the reduction of the ammonia-solvated Cu-NO3− species. The nitrate concentration in the catalysts is found to be dependent on the zeolite Cu loading and on the applied pretreatment conditions. Ammonia solvation increases the number of CuII sites available for the formation of nitrates, as confirmed by infrared spectroscopy.

Enhancing the chloramphenicol sensing performance of Cu–MoS2 nanocomposite-based electrochemical nanosensors: roles of phase composition and copper loading amount

The rational design of nanomaterials for electrochemical nanosensors from the perspective of structure–property–performance relationships is a key factor in improving the analytical performance toward residual antibiotics in food. We have investigated the effects of the crystalline phase and copper loading amount on the detection performance of Cu–MoS2 nanocomposite-based electrochemical sensors for the antibiotic chloramphenicol (CAP). The phase composition and copper loading amount on the MoS2 nanosheets can be controlled using a facile electrochemical method. Cu and Cu2O nanoparticle-based electrochemical sensors showed a higher CAP electrochemical sensing performance as compared to CuO nanoparticles due to their higher electrocatalytic activity and conductivity. Moreover, the design of Cu–MoS2 nanocomposites with appropriate copper loading amounts could significantly improve their electrochemical responses for CAP. Under optimized conditions, Cu–MoS2 nanocomposite-based electrochemical nanosensor showed a remarkable sensing performance for CAP with an electrochemical sensitivity of 1.74 μA μM−1 cm−2 and a detection limit of 0.19 μM in the detection range from 0.5–50 μM. These findings provide deeper insight into the effects of nanoelectrode designs on the analytical performance of electrochemical nanosensors.

Reactivity of styrene with tert-butyl hydroperoxide over cu-based double hydroxide catalysts

Copper(II) ions are inserted into brucite-like sheets in the Zn-Cu-Al ternary hydroxides via the precipitation route. The amount of octahedral Cu(II) sites in the Zn-Al(OH) interlayers depends on the copper loadings. The square-planar configuration (CuO) was observed in the high-copper content samples. The Cu-inserted zinc aluminum hydroxides have lamellar structure, modest surface area, and hexagonally uniform plate-like particles. All synthesized hydroxides were tested for the liquid-phase oxidation of styrene. The overall conversion of styrene obtained about 60–80 % and styrene oxide selectivity is about 70 %. The catalytic activity is correlated with the electronic configurations of copper(II) ions and reaction variables. The copper(II) ions in the brucite-like sheets proceeded through the oxidation of styrene following the metal-superpoxo pathway while the extra-lattice copper(II) ions underwent reaction with free radical route. The experimental results also indicated Cu-intercalated layered double hydroxide catalysts are more active than copper(II) oxide in the liquid-phase oxidation of styrene under the same conditions.

Catalytic Performance of Spherical MCM-41 Modified with Copper and Iron as Catalysts of NH3-SCR Process.

Spherical MCM-41 with various copper and iron loadings was prepared by surfactant directed co-condensation method. The obtained samples were characterized with respect to their structure (X-ray diffraction, XRD), texture (N2 sorption), morphology (scanning electron microscopy, SEM), chemical composition (inductively coupled plasma optical emission spectrometry, ICP-OES), surface acidity (temperature programmed desorption of ammonia, NH3-TPD), form, and aggregation of iron and copper species (diffuse reflectance UV-Vis spectroscopy, UV-Vis DRS) as well as their reducibility (temperature programmed reduction with hydrogen, H2-TPR). The spherical MCM-41 samples modified with transition metals were tested as catalysts of selective catalytic reduction of NO with ammonia (NH3-SCR). Copper containing catalysts presented high catalytic activity at low-temperature NH3-SCR with a very high selectivity to nitrogen, which is desired reaction products. Similar results were obtained for iron containing catalysts, however in this case the loadings and forms of iron incorporated into silica samples very strongly influenced catalytic performance of the studied samples. The efficiency of the NH3-SCR process at higher temperatures was significantly limited by the side reaction of direct ammonia oxidation. The reactivity of ammonia molecules chemisorbed on the catalysts surface in NO reduction (NH3-SCR) and their selective oxidation (NH3-SCO) was verified by temperature-programmed surface reactions.

Copper‐Lanthanum Catalysts for NOx and Soot Removal

AbstractThe individual and simultaneous removal of NOx by Storage and Reduction with H2 (H2‐NSR) and combustion of soot have been studied for La and CuLa catalysts. The NOx storage capacity of pure lanthanum oxide is improved either by copper addition or by using a colloidal crystal hard template for the synthesis of a macroporous structure. Although the NOx storage capacity of the CuLa macroporous material is around ten times lower regarding conventional PtBa catalysts, the kinetics of the H2‐NSR cycles are fast enough to allow high NOx removal (until 90 % removal). Lanthanum oxide catalyst prepared with uncontrolled structure has no activity for soot combustion, but the activity increases for a macroporous counterpart prepared using the colloidal crystal template because the macroporous structure improves the soot‐catalyst contact and allows the nitrogen‐oxygen surface groups yielded upon NOx chemisorption to oxidize soot. The soot combustion activity of lanthanum catalysts is also enhanced upon copper loading, because copper improves the NO2‐assisted soot combustion mechanism and favors the chemisorption of NOx, enhancing soot oxidation by nitrogen‐oxygen surface species. Finally, it is demonstrated that the simultaneous removal of NOx by H2‐NSR and soot combustion can be carried out with a CuLa catalyst at 450 °C. The simultaneous removal does not affect the combustion of soot and only has a small effect in NOx removal.

Hydrotreatment of Cellulose-Derived Bio-Oil Using Copper and/or Zinc Catalysts Supported on Mesoporous Silica-Alumina Synthesized from Lapindo Mud and Catfish Bone

Catalysts comprising copper and/or zinc supported on mesoporous silica-alumina (MSA) with a high Si/Al ratio were prepared by wet impregnation method. This study investigated the preparation, characterization, and catalytic application of the prepared catalysts for hydrotreatment cellulose-derived bio-oil. The wet impregnation was performed by directly dispersing Cu(NO3)2·3H2O and/or Zn(NO3)2·4H2O aqueous solution into MSA, followed by calcination and reduction under H2 gas stream. The acidity test revealed that metal addition on MSA support increases the acidity of catalysts. During hydrotreatment of cellulose-derived bio-oil CuZn/MSA with total acidity, copper loading, zinc loading, and specific surface area of 24.86 mmol g–1, 5.23 wt.%, 3.15 wt.%, and 170.77 m2 g–1, respectively, exhibited the best performance compared to other prepared catalysts with 90.49 wt.% conversion of liquid product.

Correction to: Effect of Copper Loading in Copper-Alumina Aerogels on Three-Way Catalytic Performance

Correction to: Effect of Copper Loading in Copper-Alumina Aerogels on Three-Way Catalytic Performance

Synthesis of poly(ethyleneimine)-functionalized mesoporous silica gel with dual loading of host ion and crosslinking for enhanced heavy metal removal in multinary solutions

Polyethyleneimine (PEI)-functionalized mesoporous silica gel (SG) was synthesized through dual loading (d-PEI-SG) of copper (Cu) as a host ion for Cu(II)-PEI complex and crosslinking with glutaraldehyde in the synthesis pathway to enhance deposition of PEI on the SG. For comparison, the PEI-functionalized SG was also prepared through single loading (s-PEI-SG) of the host ion and crosslinking with glutaraldehyde. In thermogravimetric analysis, the weight loss of d-PEI-SG at 110–500 °C (7.8%) was greater than that of s-PEI-SG (2.8%), indicating the enhanced deposition of PEI on the silica gel surface of d-PEI-SG. The elemental composition from X-ray photoelectron spectroscopy analysis demonstrated that relative quantities of carbon and nitrogen in d-PEI-SG were larger than those of s-PEI-SG. In batch tests, the maximum Cu(II) adsorption capacity of d-PEI-SG was determined to 170.4 μmol g−1, which was four times larger than that (41.8 μmol g−1) of s-PEI-SG. In a multinary solution of divalent metal ions (Cu(II), Pb(II), Zn(II), Ni(II), and Co(II)) and trivalent/tetravalent metal ions (Cu(II), Al(III), Cr(III), and Zr(IV)), d-PEI-SG had a higher Cu(II) adsorption capacity and selectivity than s-PEI-SG. Column experiments were also conducted in the multinary solution of Cu(II), Pb(II), Zn(II), Ni(II), and Co(II), demonstrating that d-PEI-SG could remove more Cu(II) than s-PEI-SG in flow-through conditions.

Copper Supplementation, A Challenge in Cattle.

Simple SummaryCopper supplementation in ruminants deserves special attention because of the narrow margin between deficiency and toxicity, both of which ruminants are susceptible to suffering from. Supplementation of copper above requirements to prevent deficiency has led to an increased number of outbreaks of copper toxicity being reported in recent years, particularly in dairy cattle. In this paper we describe the key points of copper metabolism in cattle that should be taken into consideration to guarantee an adequate copper supply while preventing toxic effects.Ensuring adequate copper supplementation in ruminants is a challenging task due to the complexity of copper metabolism in these animals. The three-way interaction between copper, molybdenum and sulphur (Cu-Mo-S) in the rumen makes ruminants, particularly cattle, very susceptible to suffering from secondary copper deficiency. Paradoxically, excessive copper storage in the liver to prevent deficiency becomes a hazard when ruminants are fed copper-supplemented diets even slightly above requirements. While cattle were traditionally thought to be relatively tolerant of copper accumulation, and reports of copper poisoning were until recently somewhat rare, in recent years an increased number of episodes/outbreaks of copper toxicity in cattle, particularly in dairy cattle, have been reported worldwide. The growing number of lethal cases reported seems to indicate that copper intoxication is spreading silently in dairy herds, urging the development of strategies to monitor herd copper status and improve farmers’ awareness of copper toxicity. In fact, monitoring studies carried out on numerous samples collected from culled animals in slaughterhouses and/or diagnostic laboratories have demonstrated that large numbers of animals have hepatic copper concentrations well above adequate levels in many different countries. These trends are undoubtedly due to copper supplementation aimed at preventing copper deficiency, as dietary copper intake from pasture alone is unlikely to cause such high levels of accumulation in liver tissue. The reasons behind the copper overfeeding in cattle are related both to a poor understanding of copper metabolism and the theory of “if adding a little produces a response, then adding a lot will produce a better response”. Contrary to most trace elements, copper in ruminants has narrow margins of safety, which must also be formulated considering the concentrations of copper antagonists in the diet. This review paper aims to provide nutritionists/veterinary practitioners with the key points about copper metabolism in cattle to guarantee an adequate copper supply while preventing excessive hepatic copper loading, which requires à la carte copper supplementation for each herd.

Neighboring Cu toward Mn site in confined mesopore to trigger strong interplay for boosting catalytic epoxidation of styrene

Herein, we report an efficient controlled approach to reach the synergetic neighboring dual-metal active sites in the confined mesopore of silica. In this approach, Mn-bearing mesoporous molecular sieve was designed in advance via a metal-assisted in-situ assembly route and further employed as a starting carrier to accommodate more extraneous Cu by impregnation. Controlling copper loading (Cu/Mn = 0.2, 0.4, and 0.6), comparative catalysts were attained and precisely characterized by key physicochemical methods. Impressively, in-situ formed highly-dispersed MnOx covered on the mesopore become the prerequisite for producing interplayed active species with neighboring dual Cu-Mn sites. Catalytic results concerning styrene epoxidation together with DRIFTS experiments and calculated bond energy variation in expected reaction intermediates demonstrated the existed synergy derived from formed neighboring Cu-Mn species via weakening and reinforcing appointed chemical bonds in intermediates. This study provides the foreseeable possibility for attaining universal synergetic catalysts in industrial heterogeneous catalysis.

Augmentation of Photocatalytic Degradation of Oxytetracycline by Cu-CdS and Deciphering the Contribution of Reactive Oxygen Species.

Production of Copper (Cu) modified Cadmium sulfide (CdS) nanomaterial, named as Cu-CdS, was successfully synthesized through hydrothermal and photo deposition method to degrade oxytetracycline (OTC) antibiotics in aqueous solution. Uniform surface loading of copper was observed on CdS using Scanning Electron Microscopy-mapping (SEM-mapping). The Cu induced improvement in the visible light absorption was observed using UV-vis absorption spectrum. Thus, this material can exhibit excellent oxytetracycline (OTC) degradation by photocatalysis. The best OTC degradation efficiency of 90% was be achieved under the optimal concentration of 4% Cu-CdS, with 0.1 g L-1 dosage (pH 5) under UV irradiation. 0.167 mg L-1 min-1 was observed as the reaction kL-H on the peripheral of the catalyst. In addition, OTC can also be degraded under visible light with removal efficiency approximately 90%. Moreover, the contribution of main reactive oxygen species (ROS), including hydroxyl radicals, superoxide radical and holes, is evaluated as 18%, 43% and 29%.

The effect of the chloride ion on chemical degradation of LIX 984N extractant

Water supply is becoming an increasingly important aspect of hydrometallurgical operations due to water deficiency. This problem may significantly lessen if the extraction processes can incorporate the usage of saltwater throughout the whole hydrometallurgical operation. In this research, the effect of chloride ion on the chemical degradation of LIX 984N was investigated. It was shown that chloride does not directly degrade LIX 984N. However, it has a catalytic effect on the hydrolysis and nitration of the extractant. The synergic effect of chloride on the extractant degradation through hydrolysis and nitration mechanism was assessed at different acidities and mixing times for up to three months. The presence of chloride ion accelerated the degradation of LIX 984N through both hydrolysis and nitration processes. Additionally, the impact of degradation processes on copper maximum loading, extractant viscosity, copper extraction, impurity entrainment, extraction selectivity, and copper stripping were assessed. The structure of the degraded extractant and its compositional changes was studied using Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC–MS) analysis. Degradation of the extractant resulted in a decrease in maximum copper loading, increasing entrainment of impurities, increasing extractant viscosity, lower copper extraction, and less efficient stripping of copper. Samples degraded in the presence of chloride functioned less efficiently in comparison to samples degraded in the absence of chloride. Moreover, structural changes were more noticeable in samples mixed with an aqueous solution containing chloride.

High Performance and Sustainable Copper-Modified Hydroxyapatite Catalysts for Catalytic Transfer Hydrogenation of Furfural

Designing and developing non-noble metal-based heterogeneous catalysts have a substantial importance in biomass conversion. Meerwein-Ponndorf-Verley (MPV) reaction is a significant pathway for eco-friendly catalytic transfer hydrogenation (CTH) of biomass derived furfural into furfuryl alcohol. In this work, a series of copper-supported hydroxyapatite (HAp) catalysts with different copper loadings (2–20 wt.%) were prepared by a facile impregnation method and tested in the reduction of furfural to furfuryl alcohol using 2-propanol as a hydrogen donor. The structural and chemical properties of the synthesised catalysts were analysed by using various techniques (XRD, N2 sorption, SEM, TEM, UV-DRS, ICP, FTIR, TPR, TPD-CO2 and N2O titration). The effect of copper loading was found to be significant on the total performance of the catalysts. The results demonstrate that 5CuHAp catalyst possess highly dispersed copper particles and high basicity compared to all other catalysts. Overall, 5CuHAp exhibited highest conversion (96%) and selectivity (100%) at 140 °C at 4 h time on stream. The optimised reaction conditions were also determined to gain the high activity.