Cobalt Loading Research Articles

Catalytic activity of cobalt and cerium catalysts supported on calcium hydroxyapatite in ethanol steam reforming

Abstract In this paper, Co,Ce/Ca10(PO4)6(OH)2 catalysts with various cobalt loadings for steam reforming of ethanol (SRE) were prepared by microwave-assisted hydrothermal and sol-gel methods, and characterized by XRD, TEM, TPR-H2, N2 adsorption-desorption measurements and cyclohexanol (CHOL) decomposition tests. High ethanol conversion (close to 100%) was obtained for the catalysts prepared by both methods but these ones prepared under hydrothermal conditions (HAp-H) ensured higher hydrogen yield (3.49 mol H2/mol C2H5OH) as well as higher amount of hydrogen formed (up to 70%) under reaction conditions. The superior performance of 5Co,10Ce/HAp-H catalyst is thought to be due to a combination of factors, including increased reducibility and oxygen mobility, higher density of basic sites on its surface, and improved textural properties. The results also show a significant effect of cobalt loading on catalysts efficiency in hydrogen production: the higher H2 yield exhibit catalysts with lower cobalt content, regardless of the used synthesis method.

Lignin fragmentation over magnetically recyclable composite Co@Nb2O5@Fe3O4 catalysts

Recoverable catalysts for lignin fragmentation were prepared as Xwt%Co@Nb2O5@Fe3O4 composites having magnetite as an inner core. A shell of niobia covering the magnetic nanoparticles (leading to intermediate Nb2O5@Fe3O4 composite) was deposed from a solution of ammonium niobate (V) oxalate complex by precipitation with NH3. Finally, the deposition of cobalt following the deposition–precipitation method generated the Xwt%Co3O4@Nb2O5@Fe3O4 composites that were reduced with hydrogen to Xwt%Co@Nb2O5@Fe3O4. Catalysts with loading of cobalt in the range X=1–20 were prepared using this procedure. The different steps of the preparation were followed using various techniques such as surface area measurements, XRD, Raman and NH3-DRIFT spectroscopy, XPS, Mössbauer and TEM. On this basis it was concluded that the synthesized composites exhibit both Lewis and Brønsted acid sites associated with the niobia shell and contain finely dispersed cobalt nanoparticles. The fragmentation of lignin occurred on the constituent parts of this composite, i.e. Fe3O4, Nb2O5, Nb2O5@Fe3O4 but with lower performances. The addition of cobalt (Co@Nb2O5@Fe3O4 catalysts) led to a complete fragmentation of lignin where the dominant fragments were those containing C20–C28 molecules. This catalytic behavior is explained on the capability of niobia to catalyze the acidic hydrolysis of the β-O-4′ bounds and of Co to break the C–C bonds via hydrogenolysis. The optimization of the catalyst composition indicated a loading of 4wt% as optimal. Working at 180°C and 10atm H2 this catalyst allowed a conversion of 53% leading to a mixture containing over 96% in C20–C28 and C29–C37 fragments. The investigated catalysts were completely recyclable as it was showed in six successive cycles. No leaching of the elements included in the composition was determined by ICP-OES.

Nitrous oxide decomposition over Co/SBA-15 catalysts: the influence of metal loading, cobalt precursor, and solvent effect

The influence of cobalt loading (10–50 wt-%Co), cobalt precursor, and solvent on the physico-chemical and catalytic properties of mesoporous Co/SBA-15 catalysts for the N2O decomposition reaction has been investigated. Catalysts were characterised by N2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). For Co/SBA-15 catalysts prepared from Co(II) nitrate, the dispersion decreased and the extent of cobalt reduction increased with cobalt loading. A maximum N2O conversion was found for the sample with ca. 30 wt-% Co loading. At similar cobalt loading (ca. 30 wt-%), a low dispersion and a stronger cobalt–support interaction leading to the formation of low reducible cobalt silicates was observed for Co/SBA-15 samples prepared from acetate precursors as compared to that derived from cobalt(II) nitrate, as evidenced by TPR. The former catalysts showed a low N2O decomposition activity. Moreover, at every Co loadings, the catalysts prepared in water exhibited much higher activities than those prepared in ethanol solvent, which could be related to the low reducibility of cobalt species in the latter catalysts. Finally, at comparable Co loading Co/SBA-15 catalysts (nitrate precursor) were more active than a Co/SiO2 and Co/Al2O3 sample.

Effect of calcination and metal loading on the characteristics of Co/NaY catalyst for liquid-phase hydrogenation of ethyl lactate to 1,2-propanediol

Co/NaY catalysts prepared by impregnation of NaY with a cobalt nitrate-ethanol solution were used to catalyze liquid-phase hydrogenation of ethyl lactate to 1,2-propanediol (1,2-PDO). To elucidate the effect of calcination conditions and cobalt loading, the catalysts were characterized using XRD, N2 physical adsorption, H2-TPR, XPS, H2-TPD, and TEM. The results show that both high calcination temperature and high amount of Co loading result in relatively large Co3O4 particles. The reduced cobalt catalysts consist of three cobalt species, including metallic Co, cobalt oxides and cobalt species interacting with zeolite (cobalt aluminate/silicate), due to incomplete reduction of cobalt species. The absence of the characteristic peak of metallic Co in the XRD pattern confirms its high dispersion on NaY, in agreement with the TEM results. H2-TPD effectively quantifies the number of surface metallic Co sites, which correlates linearly with the ethyl lactate conversion. This correlation indicates that metallic Co is the active site for ethyl lactate hydrogenation. A complete conversion of ethyl lactate with a selectivity of 96% to 1,2-PDO has been achieved over the 6Co/NaY-673-5 catalyst.

Catalytic co-pyrolysis of paper biomass and plastic mixtures (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) and product analysis

Catalytic co-pyrolysis of biomass and plastics (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) has been performed in a fixed-bed reactor in presence of cobalt based alumina, ceria and ceria-alumina catalysts to analyze the product distribution and selectivity. Catalysts are synthesized using co-precipitation method and characterized by BET (Brunauer–Emmett–Teller) surface area and XRD analysis. The effect of catalytic co-pyrolysis at different temperature with product distribution has been evaluated. The results have clearly shown the synergistic effect between biomass and plastics, the liquid products gradually increases forming with rise in the plastic content in the blend. Gaseous products have yielded most during pyrolysis of blend having biomass/plastics ratio of 5:1 with the presence of 40% Co/30% CeO2/30% Al2O3 catalyst with hydrogen gas production touched its peak of 47 vol%. Catalytic performance enhanced with increase with the cobalt loading, with best performance attributing to 40% Co/30% CeO2/30% Al2O3 catalyst.

Fischer-Tropsch synthesis: Cobalt catalysts on alumina having partially pre-filled pores exhibit higher C5+ and lower light gas selectivities

Sequential impregnation and calcination were used to fill the pores of a commercial alumina support with alumina. In this manner, two different pore-modified alumina supports were synthesized. To account for the diminished pore size, cobalt loadings were lowered as appropriate to ensure a similar cobalt size range (e.g., clusters 14–18nm in diameter) and comparable extents of reduction. This was confirmed by measurements from TPR, hydrogen chemisorption/pulse reoxidation, and EXAFS/XANES spectroscopies. Catalysts were tested using a slurry phase CSTR reactor at commercially relevant FTS conditions. Selectivities were compared at both high and low levels of conversion for the catalyst series. Decreasing the pore length, as measured by PSD data, appears to lessen the adverse effect that the higher relative diffusional rate of hydrogen versus carbon monoxide has on the H2/CO surface fugacity ratio on the catalyst surface. That is, moving the cobalt particles closer to the pore mouth may prevent the H2/CO ratio from being augmented at the surface of cobalt particles due to diffusion or other factors, and inhibits excessive chain termination that would lead to higher light product selectivities. Pore filling thus results in a catalyst that is similar to an egg-shell catalyst. With increased pore filling by alumina, C1C4 light gas selectivities decreased, in a systematic way, by as much as 33% (relative basis), and the C5+ selectivity improved by as much as 10.3% (relative basis) in comparison with the 22.4%Co/Al2O3 (IWI) reference catalyst. This greater effectiveness offers an opportunity for more environmentally benign chemical processing.

Preparation of a high performance cobalt catalyst for CO2 reforming of methane

The novel silica supported cobalt catalysts powders promoted by ruthenium and zirconium (CRZS) were prepared via a coprecipitation method for the catalytic CO2 reforming. The optimum metals loadings and pH of solution were systematically investigated in order to obtain a high performance and coke resistant catalyst. The most active, stable, and coke resistance catalyst was found in the catalyst prepared at pH 1 with the combination of 14.68wt.%, 0.14wt.%, 5.00wt.%, and 80.00wt.%, respectively for cobalt, ruthenium, zirconium and silica. BET, XRD, TPR, and H2 chemisorption analyzer found that the phenomena of Co3O4 cluster enlargement as the increase of cobalt loadings, the higher reduction degree and pore diameter as the increase of ruthenium loadings, and the inhibition of strong Co–SiO2 interaction in the proper zirconium loading were confirmed as the variation of metals loadings. The variable of pH solution during catalysts preparation gave significant effects on the catalysts stability and coke formation. The deactivation of catalyst prepared in low pH was related with the presence of surface ZrO of catalyst without any relation with coke formation. The obtained parameters of methane consumption rate based on Eley–Rideal mechanism showed that the surface chemical reaction between methane and surface oxygen became the rate-determining step of the reaction.

Synergistic Promotion of Co/SiO2 Fischer–Tropsch Catalysts by Niobia and Platinum

Transition-metal oxides and noble metals are well-known selectivity and activity promoters in cobalt-based Fischer–Tropsch catalysis. Niobia has been shown as an effective selectivity promoter as support material; however, its low porosity limits the cobalt loading. To combine the selectivity-promoting properties of niobia with a highly porous support, niobia-modified silica was prepared and applied as a support for Co and PtCo catalysts with cobalt loadings up to 21 wt %. Niobia promotion was found to increase the C5+ selectivity at 1 bar; however, it appeared to be ineffective at 20 bar. Promotion of Co/SiO2 by a combination of platinum and niobia yielded an increase of the cobalt-weight normalized activity by a factor of 2–3 in the case of amorphous niobia and by a factor of 3–4 with niobia nanocrystals present, due to both an increased number of active sites and an increased cobalt-surface specific activity (turnover frequency).

Optimisation of Cobalt Loading on γ-Al2O3 for Total Oxidation of Methane

A series of Co/γ-Al2O3 catalysts with different Co (5–30 wt. %) loading were tested for methane oxidation. The catalysts were prepared by deposition precipitation method and calcined at 600°C for 4 h. The prepared samples were characterised by TGA, XRD. Among all the studied catalyst, Co (18 wt.%)/ γ-Al2O3 showed the highest activity for complete oxidation of methane at a temperature of 490°C. The catalytic activity of the tested samples follows Co (18 > 19 > 20 > 21 > 17 > 15 > 25 > 10 > 30 wt. %)/γ-Al2O3. The catalytic behaviour of these samples towards CH4 oxidation was found to increase with cobalt loading, though a plateau was reached at concentration of 18 wt. % Co content. It was observed that when cobalt (with the concentration of 18%) is supported on γ-alumina, it acts as a highly active catalyst for methane oxidation. However, with further increase in the cobalt contents on γ-alumina, the catalytic activity decreases. The oxidation of methane was carried out in a tubular fixed-bed reactor. A fixed weight (500 mg) of the catalyst was taken and 1.5% CH4 (1.5 mL/min) in air (148.5 mL/min) at a total feed rate of 150 mL/min was used in the reactor.

Chemically drilling carbon nanotubes for electrocatalytic oxygen reduction reaction

Carbon nanotubes (CNTs) were chemically drilled by supporting cobalt oxide in a controllable way. A series of drilled CNTs with different Co loadings were prepared, characterized and used as the oxygen reduction reaction electrocatalysts. The results show that for the drilled CNTs with the cobalt loading less than 8wt%, the defects or edge carbons as dominating factor increase the electrocatalytic oxygen reduction reaction (ORR) activity; for the drilled CNTs with the cobalt loading more than 12wt%, the electron transfer resistance becoming the main determinant decreases the ORR activity. The properly drilled CNTs show dramatically enhanced ORR performance than the original CNTs.

Catalyst and Catalysis for Fischer-Tropsch Synthesis: A Comparative Analysis of Iron and Cobalt Catalysts on SBA-15

The influence of Cobalt and iron loading, cobalt and iron precursor, and the effect of promoters(Mg and Mn) on the physico-chemical properties as well as the catalytic properties and structural appearance of mesopourous Co/ SBA-15, Fe/SBA-15 and bimetallic Fe, Co/SBA-15 catalysts for Fischer-Tropsch (FTS) reaction is investigated. The various prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron micropscope (SEM), Energy dispersion X-ray diffraction (EDX) and Temperature programmed reduction (TPR). For the Co/SBA-15 and Fe/SBA-15 prepared and promoted with Magnesium and manganese (Mg, Mn), the dispersion of the metal loaded (Fe, Co) increases significantly when compared to the un-promoted Co/SBA-15 and Fe/SBA-15, and the dispersion of metal loaded (Co, Fe) was found to be higher with Mg than Mn promoter. The bimetallic catalyst was also found to have a higher dispersion of the metals than a single metal loaded catalyst (Co/SBA-15, Fe/SBA-15). Promoting the catalyst with Mn increases dispersion but it was said to decrease reducibility leading to a catalyst that is less reactive than the un-promoted one [1-3]. The mesopourous catalyst prepared did not show any crystal growth in their meso-channels which propose the dispersion of the active metals on the mesopore and the formation of tiny crystals (nanocrystal) undetectable by the X-ray diffractogram. The absence of an intense peak of the crystals (Co3O4, Fe3O4) at an expected angle might be due to the existence of ions of cobalt and iron which might be existing as a nanocluster or due to the disintegration of the mesopores structures.

Kinetics and mechanism of magnesium sulphite oxidation promoted by a novel cobalt-based molecular sieve catalyst

The oxidation of magnesium sulphite is crucial in recycling the byproduct of magnesium desulphurisation. In this study, a novel cobalt-based catalyst was prepared using a wet impregnation method by loading cobalt species on a molecular sieve carrier. The catalyst was characterised using scanning electron microscopy, X-ray fluorescence, Brunauer–Emmett–Teller analysis, X-ray diffraction, and energy dispersive X-ray spectroscopy. The catalyst was confirmed to be a mesoporous material. The macroscopic kinetics of magnesium sulphite oxidation catalysed by this cobalt-based catalyst was investigated in a stirred tank reactor. The results showed that reaction orders with respect to catalyst, magnesium sulphite, and oxygen concentrations were 0.39, 0, and 0.41, respectively. The apparent activation energy was 35.2kJmol−1. In addition, a comparison of the rates of external diffusion, internal diffusion, and intrinsic reaction revealed that the internal diffusion of oxygen might be the rate-controlling step of magnesium sulphite oxidation. The results provide a new approach for recycling the magnesium desulphurisation byproduct.

Fabrication and Characterization of Amorphous Cobalt-Doped Molybdenum Sulfide for Hydrogen Evolution Reaction.

In the present study, hydrogen evolution reaction (HER) by alkaline water electrolysis was conducted without using a precious metal catalyst. We synthesized an amorphous cobalt-doped molybdenum sulfide by electrodeposition using different cobalt loadings. The amorphous Co-MoSx produced was characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The cobalt doping and sulfidation procedure resulted in the successful fabrication of a candidate catalyst for the catalytic hydrogen evolution in alkaline solution with high intrinsic activity. Cobalt incorporated amorphous MoSx exhibited 3 times higher HER activity than non-promoted MoSx.

Cobalt modified red mud catalytic ozonation for the degradation of bezafibrate in water: Catalyst surface properties characterization and reaction mechanism

A systematic investigation of the catalytic reaction mechanism of surface cobalt-loaded red mud (RM) was carried out using the reaction kinetics analysis and catalyst surface property characterization. First, multiple characterization methods (XRD, FT-IR and XPS) were used to investigate the variation of surface texture and chemical properties of the catalyst after surface cobalt loading. Second, the contributions of molecular ozone (39.22%), hydroxyl radicals (45.20%), and surface adsorption (15.57%) for bezafibrate (BZF) degradation by Co/RM were identified by the reaction kinetic analysis using the tertiary butanol used as an organic quencher, confirming that surface cobalt loading promoted the role of the hydroxyl radical reaction. The phosphate was used as an inorganic probe to study the role of the solution and surface reactions in catalytic ozonation. The presence of phosphate inhibited 17.5%, 25.1%, and 27.2% efficient when phosphate concentration was 0.0104, 0.0208, and 0.0416mM, respectively. The kinetics analysis showed that the inhibiting effect of phosphate on BZF degradation was due to quenching of HO in solution, and not the surface chelation reaction. However, surface cobalt loading enhanced this surface interface reaction. Finally, the relationship between surface texture/chemical properties and catalytic activity was established, confirming that surface cobalt loading developed mesopores leading to an increase of the specific surface area. This was favorable for the catalytic activity. Co3O4 covered over the mesopore surface of RM and developed the surface hydroxyl group by the chemical water deduced from the cobalt surface loading. This is the main catalytic reaction site.

Acidic/Basic Oxides-Supported Cobalt Catalysts for One-Pot Synthesis of Isophorone Diamine from Hydroamination of Isophorone Nitrile

A series of cobalt-based catalysts supported on several acidic/basic oxides were prepared by the incipient wetness impregnation method and applied for the one-pot synthesis of isophorone diamine (IPDA) from hydroamination of isophorone nitrile (IPN). The effects of the supports and cobalt loading on the performance of the catalysts were investigated. The results showed that the Co/SiO2 catalyst with 20 wt % Co loading gave the highest conversion of IPN (90.9%) and yield of IPDA (70.4 mol %) among the supported cobalt catalysts used in this work, and it could be reused eight times without a significant decrease in the catalytic performance, which was much better than that from the commercial Raney Co. Meanwhile, the possible intermediates and reaction pathways during hydroamination of IPN were provided.

Selective catalytic reduction of NO by methane over the Co/MOR catalysts in the presence of oxygen

AbstractA series of Co/MOR catalysts were prepared by impregnation method and used in the selective catalytic reduction of nitric oxide with methane (CH4-SCR). These catalysts were characterized by XRD, BET, TG-MS, H2-TPR, NH3-TPD and NO-TPD; their performance in the CH4-SCR of NO was investigated. The results showed that cobalt species exist as Co3O4 spinal in the Co/MOR catalysts; the acidity and redox and NO absorption/desorption ability of the Co/MOR catalysts are changed after the incorporation of cobalt in MOR zeolite, in comparison with pure MOR zeolite. The catalytic performance of Co/MOR is closely related to its redox and NO adsorption/desorption ability, which are dependent on the cobalt loading. The Co(10)/MOR catalyst with a cobalt loading of 10% exhibits high activity in the CH4-SCR of NO; over it the conversion of nitric oxide reaches 54.2% at 330°C.

Phenol oxidation by air using a Co (II) Salen complex catalyst supported on nanoporous materials: synthesis, characterization and kinetic analysis

Cobalt (II) Salen complex catalysts were synthesized and immobilized through covalent bonds on synthetic silica (SBA-15) and commercial supports, including silica (SiO2), alumina (Al2O3) and granular activated carbon (C). Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV–vis), diffuse reflectance ultraviolet-visible spectroscopy (DR–UV–vis) and X-ray diffraction (XRD) were used to characterize and follow the synthesis of the cobalt (II) Salen complex The UV–vis absorption spectra confirmed the formation of the Salen ligand and its coordination with the Co (II). FTIR spectra showed the incorporation of the Co Salen complex and its anchoring to the support was confirmed by DR–UV–vis. The catalytic activity was evaluated measuring the oxidation of phenol by air in a buffer solution using micellar electrokinetic chromatography (MEKC). The effects of support, initial substrate concentration, pH, oxidant (O2 vs H2O2) and temperature were investigated. The best catalytic performance was obtained when the Co Salen complex was immobilized on SBA-15 (Co Salen/SBA-15). Conversely, the results suggest that the activated carbon promoted the irreversible adsorption of the substrate. The Co Salen support was also characterized by scanning electron microscopy (SEM) to elucidate the morphology. Elemental analysis using energy dispersive X-ray spectroscopy (EDX) exhibited better Co Salen dispersion on the SiO2 and SBA-15 supports. The cobalt loading calculated from atomic absorption spectroscopy (AAS) was 0.22, 0.20, 0.14 and 0.09mmol/g for the Co Salen supported on SiO2, SBA-15, Al2O3 and C, respectively. A specific surface area of 736.13m2/g and a nanoporosity of 3.62nm were obtained for SBA-15 using N2 physisorption analysis; this high specific surface area is characteristic of SBA-15 and plays a critical role in the reported activity. According to these results and the corresponding data analysis, the catalyst promoted the oxidation of phenol with a reversible first-order kinetic reaction in air, as observed from the data obtained at 3 different temperatures (25, 38 and 50°C). These results enabled the calculation of activation energy values of 63 and 57kJ/mol. In addition, the Co Salen/SBA-15 showed very good selectivity toward the production of catechol, which is one of the most important precursors in the chemical industry.

Properties of Lewatit® TP272, a commercial solvent impregnated cation exchange resin for cobalt recovery

The typical hydrometallurgical processing of nickel and cobalt ores involves the precipitation of a mixed nickel–cobalt intermediate product. Alternatively, cobalt could be separated from nickel while in the aqueous phase using solvent extraction. However, solvent extraction has some problems including the need for considerable area for the separators, management of fire hazard, and operational issues such as contamination with organic cross-over with sequential solvent extraction unit operations. The use of an ion exchange resin can mitigate some of these issues; however, conventional cation exchange resins are not sufficiently selective for cobalt over nickel. Solvent impregnated resin offers the engineering advantages of ion exchange resin and the chemical selectivity of the solvent extraction process. This paper describes key properties of a new commercial solvent impregnated resin, Lewatit® TP272, including cobalt and nickel loading as a function of pH and cobalt loading isotherms at pH 5.5 and 5.0 which are identified as the ideal conditions to recover cobalt. The chemical degradation of this solvent impregnated resin was also determined by exposing the resin to greater than pH 6 solutions, which are conditions outside the recommended operating range for this resin. The capacity of the degraded resin was restored by reimpregnating the resin using a Cyanex® 272-ethanol–water mixture. Optical images of resin containing the blue cobalt complex reveal the porous structure.

Hydrogen Activation on the Promoted and Unpromoted ReS2 (001) Surfaces under the Sulfidation Conditions: A First-Principles Study

Hydrogen activation on the promoted and promoter-free ReS2(001) surfaces under the sulfidation conditions is studied by means of periodic density function theory (DFT) calculations within the generalized gradient approximation. First, surface-phase diagrams are investigated by plotting the surface free energy as a function of the chemical potential of S (μS) on the unpromoted and promoted ReS2 (001) surfaces with different loadings of nickel, cobalt, tungsten, and tantalum. The results show that on the unpromoted surface sulfur coverage of 25% and on the promoted surfaces sulfur coverage of 25% as well as 25% promoter modification are the most stable conditions, respectively, under hydrodesulfurization (HDS) reaction conditions. Second, hydrogen adsorption and dissociation are explored on these preferred surfaces. It is found that hydrogen adsorbs weakly on all the surfaces studied. The physical adsorption character makes its diffusion favorable, resulting in various adsorption sites and dissociation path...

Carbon microspheres supported cobalt catalysts for phenol oxidation with peroxymonosulfate

Heterogeneous catalytic oxidation of organic pollutants has been widely applied for wastewater treatment, in which the development of highly efficient catalysts is of critical importance. In this study, carbon microspheres supported cobalt catalysts (Co/CS) were prepared by a one-pot hydrothermal method for in-situ loading cobalt onto carbon spheres, followed by calcination at 300, 400 and 500°C, respectively. Cobalt would distribute three-dimensionally in the spheres. Many characterization techniques, such as XRD, SEM, EDS and elemental mapping were applied to investigate the physicochemical properties of the supported catalysts. The catalytic activities were evaluated by decomposition of phenol solutions with sulfate radicals. It was found that the Co/CS catalysts were able to efficiently decompose phenol by activation of peroxymonosulfate (PMS). Co/CS-300, 400 and 500 can completely decompose 20ppm phenol in 15, 5 and 10min, respectively. Kinetics studies were carried out to investigate the effects of catalyst loading, PMS amount, and reaction temperature on phenol degradation efficiency.