Au/TS‐1 catalyst for propene epoxidation with H2/O2: A novel strategy to enhance stability by tuning charging sequence

For propene epoxidation with H₂ and O₂, the catalytic performance of Au/TS‐1 catalyst is extremely sensitive to preparation parameters of deposition‐precipitation (DP) method. In this work, effect of charging sequence in DP process on catalyst structure and catalytic performance of Au/TS‐1 catalyst is first investigated. For different charging sequences, the compositions of Au complexes (e.g., [AuCl(OH)₃]^?) and pore property of TS‐1 (i.e., with or without H₂O prefilling micropores) could affect the transfer of Au complexes into the micropores, resulting in different Au locations and thus significantly different catalytic performance. Notably, when TS‐1 is first filled with H₂O and then mixed with Au complexes, the reduced Au/TS‐1 catalyst could expose Au nanoparticles on the external surface of TS‐1 and show high stability. The results provide direct evidence showing that micropore blocking is the deactivation mechanism. Based on the results, a simple strategy to design highly stable Au/Ti‐based catalysts is developed. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3963–3972, 2016     

Polymer‐Based Spherical Activated Carbons in Combination with TS‐1 as Efficient Epoxidation Catalysts

The heterogeneously catalyzed epoxidation of commercially available biodiesel with aqueous H₂O₂ as an oxidant was studied over composite catalysts consisting of microporous titanium silicalite‐1 (TS‐1) as reactive and polymer‐based spherical activated carbon (PBSAC) as sorptive component. The results are compared to that of a commercial TS‐1 catalyst. The polymer‐based spherical activated carbon was applied either as a support or as an exotemplate. In the composite catalyst, the active titanium sites are utilized four times more efficiently than in the commercial TS‐1.     

Polymerbasierte sphärische Aktivkohlen in Kombination mit TS‐1 als effiziente Epoxidierungskatalysatoren

The heterogeneously catalyzed epoxidation of commercial biodiesel with aqueous H₂O₂ as oxidizing agent has been studied using composite catalysts composed of microporous titanium silicalite (TS‐1) as a reactive, and a polymer‐based spherical activated carbon as sorptive functionality. The results were compared with the performance of a commercial TS‐1 catalyst. The polymer‐based spherical activated carbon was used either as a support or as exotemplate. The efficiency of the active titanium sites was four times higher in the composite catalyst than in the commercial TS‐1 catalyst.     

Performance and Economic Assessment of the Treatment of Phenol with TiO2 Photocatalysis,Photo‐Fenton,Biological Aerated Filter,and Wetland Reactors

The performance and economic cost of the removal of phenol with TiO₂ photocatalysis, photo‐Fenton reactions, biological aerated filter (BAF), and constructed wetland (CW) reactors has been studied. The BAF achieved complete removal with a maximum phenol concentration of 200 mg·L^?1. The BAF‐CW combination provided a phenol‐free effluent with a maximum phenol concentration of 650 mg·L^?1. In both cases, a complete detoxification of the treated water was achieved at the concentrations studied. The efficiency of TiO₂ photocatalysis was limited to concentrations below 50 mg L^?1 to minimize removal reduction and toxicity of the intermediates. Photo‐Fenton was more efficient, but also more expensive because of the high cost of H₂O₂. The photo‐Fenton‐BAF combination is proposed to be the most suitable one.     

Direct Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLA) using Gold Catalysts

Supported gold catalysts, e.g., Au on Al₂O₃, Fe₂O₃, CeO₂, MnO₂, TiO₂, ZrO₂, activated carbon, titanium silicalite TS‐1, were prepared and used for the isomerization of linoleic acid (cis‐9,cis‐12‐octadecadienoic acid) to conjugated linoleic acids (CLA) in the presence of hydrogen at 165 °C in a batch reactor. The best results were obtained using a catalyst with 2 wt % Au on TS‐1, which exhibits a high selectivity (78 %) towards CLA. The two biologically active target CLA isomers, i.e., cis‐9,trans‐11‐CLA and trans‐10,cis‐12‐CLA, were the main products. During the isomerization of linoleic acid to CLA, consecutive reactions also took place. These were the hydrogenation of linoleic acid and CLA to monounsaturated octadecenoic acids and the further hydrogenation of monounsaturated acids to stearic acid. Thus, gold catalysts are capable of isomerizing linoleic acid to CLA and hydrogenating their double bonds to an extent that depends on the Au catalyst used.     

Process integration of H2O2 generation and the ammoximation of cyclohexanone

The possibility of the integration of the processes of H₂O₂ generation through isopropanol partial oxidation and ammoximation of cyclohexanone with H₂O₂ and NH₃ TS‐1 catalysed was investigated. The ammoximation of cyclohexanone over TS‐1 with isopropanol as solvent was first studied. The results show that isopropanol can be used as solvent, and the impurities in the H₂O₂ solution obtained through isopropanol oxidation with only acetone needing to be separated have no harmful effects on the ammoximation of cyclohexanone, suggesting that the process of H₂O₂ generation through isopropanol oxidation and the ammoximation of cyclohexanone could be directly integrated. Copyright © 2004 Society of Chemical Industry     

Synthesis,characterization, and thermal degradation of oligo‐2‐(morpholinoiminomethyl)phenol and its Pb(II) complex compound

The oxidative polycondensation reaction conditions of 2‐(morpholinoiminomethyl)phenol were studied with H₂O₂, air O₂, and sodium hypochloride (NaOCl) oxidants in an aqueous alkaline medium between 40 and 90°C. The structure of oligo‐2‐(morpholinoiminomethyl)phenol was characterized with ¹H‐ and ¹³C‐NMR, Fourier transform infrared, ultraviolet–visible, size exclusion chromatography, and elemental analysis techniques. Under the optimum reaction conditions, the yield of oligo‐2‐(morpholinoiminomethyl)phenol was 28% for the H₂O₂ oxidant, 12% for the air O₂ oxidant, and 58% for the NaOCl oxidant. According to the size exclusion chromatography analysis, the number‐average molecular weight, weight‐average molecular weight, and polydispersity index of oligo‐2‐(morpholinoiminomethyl)phenol were 2420 g/mol, 2740 g/mol, and 1.187 with H₂O₂, 1425 g/mol, 2060 g/mol, and 1.446 with air O₂, and 1309 g/mol, 1401 g/mol, and 1.070 with NaOCl, respectively. Thermogravimetry/dynamic thermal analysis showed that the oligo‐2‐(morpholinoiminomethyl)phenol–lead complex compound was more stable than 2‐(morpholinoiminomethyl)phenol and oligo‐2‐(morpholinoiminomethyl)phenol against thermal degradation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3795–3804, 2006     

Kinetics and Efficiency Analysis of Electrochemical Oxidation of Phenol: Influence of Anode Materials and Operational Conditions

The influence of operational parameters and anode materials on degradation kinetics, mineralization current efficiency, and energy consumption for electrochemical oxidation of phenol was studied. Phenol elimination follows pseudo‐first‐order kinetics in most cases except for the Ti/RuO₂ anode with a phenol concentration of 500 mg L^–1, where pseudo‐zero‐order kinetics is observed. The total organic carbon removal by a Ti/Sb‐SnO₂ anode follows pseudo‐first‐order kinetics in contrast to pseudo‐zero‐order kinetics by Pt and Ti/RuO₂ anodes. For a certain anode, a higher current or voltage input results in a higher reaction rate. With a Ti/Sb‐SnO₂ anode, the highest current efficiency and the lowest energy consumption are obtained, but the current efficiency decreases (increases for energy consumption) quickly as the reaction is prolonged due to the reduction of organics.     

Functionalized Ionic Liquid-Catalyzed 1-Feruloyl-sn-glycerol Synthesis

Feruloyl Glycerol (FG) is a potential antioxidant and UV absorbing ingredient in food and cosmetic industries. Transesterifications of ethyl ferulate (EF) with glycerol to synthesize FG were performed using different functionalized ionic liquids (1‐butylsulfonic‐3‐methylimidazolium tosylate, [BSO₃HMIM]TS; 1‐propylsulfonic‐3‐methylimidazolium tosylate, [PSO₃HMIM]TS; 1‐butylsulfonic‐3‐methylimidazolium trifluoromethanesulfonate, [BSO₃HMIM]OTF; 1‐butylsulfonic‐3‐methylimidazolium hydrogen sulfate, [BSO₃HMIM]HSO₄; N‐methylimidazolium hydrogen sulfate, [HMIM]HSO₄; 1‐butyl‐3‐methylimidazolium hydroxide, [BMIM]OH; 1‐butyl‐3‐methylimidazo tetrachloride molysite, [BMIM]FeCl₄; and 1‐hexyl‐3‐methylimidazo tetrachloride molysite, [BMIM]FeCl₄) as catalysts, respectively. High EF conversion (98.0 ± 1.5 %), 1‐FG (1‐feruloyl‐sn‐glycerol) yield (88.7 ± 1.1 %) and reaction selectivity for 1‐FG (90.5 ± 2.1 %) were obtained using [BSO₃HMIM]TS as catalyst. The activation energy (E_a), the Michaelis–Menten kinetic constant (K_m), and the maximum initial reaction rate (v_max) of the transesterification are 65.9 ± 3.3 kJ/mol, 1.8 ± 0.1 mol/L, and (1.6 ± 0.4) × 10^?2 mol/(L min), respectively. Effects of catalyst loading, reaction temperature, and the molar ratio of EF to glycerol on EF conversion and reaction selectivity for 1‐FG (1‐FG yield/EF conversion) were also investigated.     

Epoxidation of allyl chloride and hydrogen peroxide over titanium silicalite‐1 film on SiO2 pellet support

Titanium silicalite‐1 (TS‐1) films were prepared on SiO₂ pellet supports via an in situ hydrothermal synthesis method and were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM) and ²⁹Si magic angle spinning nuclear magnetic resonance (Si MAS NMR). The growth time of TS‐1 film had a strong effect on its morphology and the thickness and size of the crystals. The uniformity and thickness of TS‐1 films increased with increase of growth times. The epoxidation of allyl chloride (ACH) with dilute hydrogen peroxide to form epichlorohydrin (ECH) over the TS‐1 films was carried out in a fixed bed reactor. The conversion of ACH and the selectivity to ECH over the TS‐1 films of the second growth were higher than that of the first growth, the third and the fourth growth. And the conversion and selectivity as a function of time‐on‐stream gave a good stable performance in an extended test up to at least 19 h. The final steady‐state conversion and selectivity were approximately 86% and 55%, respectively. Copyright © 2007 Society of Chemical Industry     

An investigation of the selective oxidation of NH3 to N2 in gasified biomass in the presence of excess CO and H2 using zeolite catalysts

Transition metals copper and titanium substituted mesoporous silicas (Cu-HMS and Ti-HMS) were synthesized at ambient temperature by using dodecylamine (DDA) surfactant as templating agent. XRD measurements prove that incorporating titanium and especially copper into the mesostructures causes the d₁₀₀ peaks of mesoporous silicas to become shifted to lower angles, indicating progressive expansion of the lattice d-spacings upon heteroatoms Ti and especially Cu incorporating. FT-IR measurements indicate that the calcined Cu-HMS and Ti-HMS samples all exhibit a weaker absorption band near 960 cm^-1 which may be rather a fingerprint of the heteroatom on the matrix of [SiO₄] units whatever its crystallization state. Cu-HMS possesses relatively high catalytic activity for the hydroxylation of phenol with 30% aq. H₂O₂ in aqueous solution (about 36% phenol conversion and more than 95% selectivity for dihydroxybenzene isomers), but Ti-HMS has no catalytic activity under the same reaction conditions. The product distribution obtained from Cu-HMS is completely different from that of the microporous titanium silicalite zeolites (TS zeolites). This is attributed to the porous structural differences between Cu-HMS and TS zeolites. The catalytic activity of the Cu-HMS is strongly dependent on the nature of the solvent; the Cu-HMS does not have any catalytic activity in the presence of organic solvents such as methanol or acetone instead of water. A reusing test of the recovered Cu-HMS indicates that the recovered catalyst suffers almost loss of activity and must be regenerated by calcination in air at 873 K in order to recover its activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of poly(1‐hexene)s end‐functionalized with phenols

Electrophilic alkylations of phenol/2,6‐dimethylphenol were performed with vinylidene‐terminated poly(1‐hexene)s using BF₃·OEt₂ catalyst. Vinylidene‐terminated poly(1‐hexene)s with M_n varying from 400 to 10000 were prepared by bulk polymerization of 1‐hexene at 50 to ?20 °C using Cp₂ZrCl₂/MAO catalysts. The phenol/2,6‐dimethylphenol‐terminated poly(1‐hexene)s was characterized by NMR (¹H, ¹³C), UV, IR and vapor phase osmometer (VPO). The isomer distribution (ortho, para and ortho/para) was determined by ¹³P NMR using a phosphitylating reagent, namely 2‐chloro‐1,3,2‐dioxaphospholane. The number‐average degree of functionality (F_n) >0.9 with >95% para selectivity could be achieved using low‐molecular‐weight oligomers of poly(1‐hexene)s. Copyright © 2005 Society of Chemical Industry     

Highly stable Fe/γ‐Al2O3 catalyst for catalytic wet peroxide oxidation

BACKGROUND: A highly stable Fe/γ‐Al₂O₃ catalyst for catalytic wet peroxide oxidation has been studied using phenol as target pollutant. The catalyst was prepared by incipient wetness impregnation of γ‐Al₂O₃ with an aqueous solution of Fe(NO₃)₃· 9H₂O. The influence of pH, temperature, catalyst and H₂O₂ doses, as well as the initial phenol concentration has been analyzed. RESULTS: The reaction temperature and initial pH significantly affect both phenol conversion and total organic carbon removal. Working at 50 °C, an initial pH of 3, 100 mg L^?1 of phenol, a dose of H₂O₂ corresponding to the stoichiometric amount and 1250 mg L^?1 of catalyst, complete phenol conversion and a total organic carbon removal efficiency close to 80% were achieved. When the initial phenol concentration was increased to 1500 mg L^?1, a decreased efficiency in total organic carbon removal was observed with increased leaching of iron that can be related to a higher concentration of oxalic acid, as by‐product from catalytic wet peroxide oxidation of phenol. CONCLUSION: A laboratory synthesized γ‐Al₂O₃ supported Fe has shown potential application in catalytic wet peroxide oxidation of phenolic wastewaters. The catalyst showed remarkable stability in long‐term continuous experiments with limited Fe leaching, < 3% of the initial loading. Copyright © 2010 Society of Chemical Industry     

Influence of technological parameters on the epoxidation of 1‐butene‐3‐ol over titanium silicalite TS‐2 catalyst

BACKGROUND: The influence of technological parameters on the epoxidation of 1‐butene‐3‐ol (1B3O) over titanium silicalite TS‐2 catalyst has been investigated. Epoxidations were carried out using 30%(w/w) hydrogen peroxide at atmospheric pressure. The major product from the epoxidation of B3O was 1,2‐epoxybutane‐3‐ol, with many potential applications. RESULTS: The influence of temperature (20–60 °C), 1B3O/H₂O₂ molar ratio (1:1–5:1), methanol concentration (5–90%(w/w)), TS‐2 catalyst concentration (0.1–6.0%(w/w)) and reaction time (0.5–5.0 h) have been studied. CONCLUSION: The epoxidation process is most effective if conducted at a temperature of 20 °C, 1B3O/H₂O₂ molar ratio 1:1, methanol concentration (used as the solvent) 80%(w/w), catalyst concentration 5%(w/w) and reaction time 5 h. Copyright © 2009 Society of Chemical Industry     

Photocatalytic Destruction of Phenol by TiO2Powders

In this study the photocatalytic destruction of phenol in an aqueous suspension of illuminated TiO₂ was investigated. The experiments were carried out using a Pyrex annular photoreactor. The effects of some parameters such as pH, loading of TiO₂, flow rate of O₂ and temperature on the photocatalytic destruction rate of phenol were examined. It was observed that the flow rate of O₂ has no considerable effect on the destruction of phenol over the range of 2–3.5 L min^–1. The photodestruction of phenol followed the pseudo first‐order kinetics of the Langmuir‐Hinshelwood model giving an activation energy of 16.2 kJ mol^–1.     

An Integrated Process of H2O2 Production through Isopropanol Oxidation and Cyclohexanone Ammoximation

The possibility of the integration of the processes of H₂O₂ production through isopropanol partial oxidation and the direct ammoximation of cyclohexanone with H₂O₂ and NH₃ catalyzed by TS‐1 was investigated. The results of isopropanol partial oxidation showed that around 7.5 % yield of H₂O₂ was obtained at 110 °C, 10 atm, 2 h, and after fractionation, a H₂O₂ solution with the typical composition 25.2 wt.‐% H₂O₂, 10.3 wt.‐% isopropanol, 0.29 wt.‐% acetone, 0.45 wt.‐% phosphoric acid and 0.43 wt.‐% acetic acid was obtained. The presence of these impurities up to the above levels did not appreciably influence the ammoximation of cyclohexanone in terms of the conversion of cyclohexanone and the selectivity to cyclohexanone oxime. The results indicate that the processes of H₂O₂ production through isopropanol partial oxidation and the ammoximation of cyclohexanone can be integrated.     

A new pH‐based procedure to model toxic effects on nitrifiers in activated sludge

A combination of a titration experiment and a biokinetic parameter estimation procedure is proposed as an experimental tool to study the kinetics of NH₄⁺‐oxidizing bacteria in activated sludge. The method was used to quantify the effect of low concentrations of a toxic compound on the maximum substrate removal capacity and the substrate affinity constant (K_NH) of NH₄⁺‐oxidizing bacteria in activated sludge samples. Experiments in the presence of increasing concentrations of a toxic compound (CN⁻, 3,5‐DCP, Cu²⁺ and phenol) were performed with nitrifying activated sludge samples obtained from two full‐scale wastewater treatment plants. The repeatability of the proposed procedure was found to be sufficient to deduce trends in the behavior of the NH₄⁺‐N‐oxidizing bacteria based on one series of experiments with increasing toxicant concentrations. The experimental results showed that the two sludge samples reacted completely differently in the presence of a certain concentration of the same toxic compound. For phenol, the shape of the titration curves did not correspond any longer to a simple Monod model. In this case, titration curves could be described by a model including both nitrification inhibition by phenol and degradation of the phenol by heterotrophic bacteria. © 1999 Society of Chemical Industry     

Synthesis and cure kinetics of liquefied wood/phenol/formaldehyde resins

Wood liquefaction was conducted at a 2/1 phenol/wood ratio in two different reactors: (1) an atmospheric three‐necked flask reactor and (2) a sealed Parr reactor. The liquefied wood mixture (liquefied wood, unreacted phenol, and wood residue) was further condensed with formaldehyde under acidic conditions to synthesize two novolac‐type liquefied wood/phenol/formaldehyde (LWPF) resins: LWPF1 (the atmospheric reactor) and LWPF2 (the sealed reactor). The LWPF1 resin had a higher solid content and higher molecular weight than the LWPF2 resin. The cure kinetic mechanisms of the LWPF resins were investigated with dynamic and isothermal differential scanning calorimetry (DSC). The isothermal DSC data indicated that the cure reactions of both resins followed an autocatalytic mechanism. The activation energies of the liquefied wood resins were close to that of a reported lignin–phenol–formaldehyde resin but were higher than that of a typical phenol formaldehyde resin. The two liquefied wood resins followed similar cure kinetics; however, the LWPF1 resin had a higher activation energy for rate constant k₁ and a lower activation energy for rate constant k₂ than LWPF2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Epoxidation of allyl alcohol with hydrogen peroxide over titanium silicalite TS‐2 catalyst

The influence of the technological parameters on the course of the epoxidation of allyl alcohol with 30% H₂O₂ in the presence of titanium silicalite TS‐2 catalyst and methanol as a solvent was studied. The process was performed in an autoclave at the autogenic pressure. The influence of temperature in the range 20–120 °C, molar ratio of allyl alcohol/H₂O₂ (1:1–10:1), methanol concentration in the reaction mixture (10–80% w/w), catalyst TS‐2 concentration (0.1–2.0% w/w) and reaction time (1–8 h) were investigated. The functions describing the process were: selectivity of transformation to glycidocidol in relation to allyl alcohol consumed, selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed, conversions of allyl alcohol and hydrogen peroxide. Copyright © 2007 Society of Chemical Industry     

Properties of phenol‐formaldehyde resins prepared from phenol‐liquefied lignin

In this study, alkaline lignin (AL), dealkaline lignin (DAL), and lignin sulfonate (SL) were liquefied in phenol with sulfuric acid (H₂SO₄) or hydrochloric acid (HCl) as the catalyst. The phenol‐liquefied lignins were used as raw materials to prepare resol‐type phenol‐formaldehyde resins (PF) by reacting with formalin under alkaline conditions. The results show that phenol‐liquefied lignin‐based PF resins had shorter gel time at 135°C and had lower exothermic peak temperature during DSC heat‐scanning than that of normal PF resin. The thermo‐degradation of cured phenol‐liquefied lignin‐based PF resins was divided into four temperature regions, similar to the normal PF resin. When phenol‐liquefied lignin‐based PF resins were used for manufacturing plywood, most of them had the dry, warm water soaked, and repetitive boiling water soaked bonding strength fitting in the request of CNS 1349 standard for Type 1 plywood. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011