Kinetics of the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation

In this study,high-gravity intensified heterogeneous catalytic ozonation is utilized for treatment of phenol-containing wastewater,and the kinetics of the direct reaction between ozone and phenol in the presence of excess tertiary butanol(TBA)is investigated.It is revealed that the direct reaction between ozone and phenol in the rotating packed bed(RPB)follows the pseudo-first-order kinetics with a reaction rate constant higher than that in the conventional bubbling reactor(BR).Under different conditions of temperature,initial pH,high-gravity factor,and gaseous ozone concentration,the apparent reaction rate constant varies in the range of 0.0160–0.115 min-1.An empirical power-exponential model is established to characterize the effects of these parameters on the direct reaction between ozone and phenol by high-gravity intensified heterogeneous catalytic ozonation.

Highly reactive and reusable heterogeneous activated carbons-based palladium catalysts for Suzuki-Miyaura reaction

Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch procedure and continuous-flow procedure) were used to study the variations of reaction processing. The heterogeneous catalysts presented excellent reactivity and recyclability for iodobenzene and bromobenzene substrates in batch mode, which can be attributed to stabilization of Pd nanoparticles by the thiol and amino groups on the AC supports. However, significant dehalogenation in the reaction mixture and Pd leaching from the heterogeneous catalysts were observed in continuous-flow mode.This unique phenomenon in continuous-flow mode resulted in a dramatic decline in reaction selectivity and durability of heterogeneous catalysts comparing with that of batch mode. In addition, the heterogeneous Pd catalysts with thiol-and amino-modified AC supports exhibited different reactivity and durability in batch and continuous-flow mode owing to the difference of interaction between Pd species and AC supports.

Optimization of a digested sludge-derived mesoporous material as an efficient and stable heterogeneous catalyst for the photo-Fenton reaction

The anaerobic digestion of sludge has recently received increased interest because of the potential to transform organic matter into methane‐rich biogas. However, digested sludge, the residue produced in that process, still contains high levels of heavy metals and other harmful substances that might make traditional disposal difficult. We have devised a facile method of converting digested sludge into a mesoporous material that acts as an effective and stable heterogeneous catalyst for the photo‐Fenton reaction. A comparison of the removal of rhodamine B under different conditions showed that FAS‐1‐350, which was synthesized by mixing the digested sludge with a 1 mol/L（NH4）2Fe（SO4）2 solution followed by calcination at 350 °C, exhibited the best catalytic activity owing to its faster reaction rate and lower degree of Fe leaching. The results indicate that Fe^（2＋）‐loaded catalysts have significant potential to act as stable and efficient heterogeneous promoters for the photo‐Fenton reaction, with better performance than Fe^3＋‐loaded catalysts because the Fe（II）/Fe（III）compounds formed in the calcination process are necessary to sustain the Fenton reaction. This protocol provides an alternative, environmentally friendly method of reusing digested sludge and demonstrates an easily synthesized mesoporous material that effectively degrades azo dyes.

Numerical Study on the Impacts of Heterogeneous Reactions on Ozone Formation in the Beijing Urban Area

The air quality model CMAQ-MADRID （Community Multiscale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization and Dissolution） was employed to simulate summer O3 formation in Beijing China, in order to explore the impacts of four heterogeneous reactions on O3 formation in an urban area. The results showed that the impacts were obvious and exhibited the characteristics of a typical response of a VOC-limited regime in the urban area. For the four heterogeneous reactions considered, the NO2 and HO2 heterogeneous reactions have the most severe impacts on O3 formation. During the O3 formation period, the NO2 heterogeneous reaction increased new radical creation by 30%, raising the atmospheric activity as more NO→NO2 conversion occurred, thus causing the O3 to rise. The increase of O3 peak concentration reached a maximum value of 67 ppb in the urban area. In the morning hours, high NO titration reduced the effect of the photolysis of HONO, which was produced heterogeneously at night in the surface layer. The NO2 heterogeneous reaction in the daytime is likely one of the major reasons causing the O3 increase in the Beijing urban area. The HO2 heterogeneous reaction accelerated radical termination, resulting in a decrease of the radical concentration by 44% at the most. O3 peak concentration decreased by a maximum amount of 24 ppb in the urban area. The simulation results were improved when the heterogeneous reactions were included, with the O3 and HONO model results close to the observations.

MCM-41 anchored sulfonic acid (MCM-41-R-SO_3H):A mild,reusable and highly efficient heterogeneous catalyst for the Biginelli reaction

An efficient three-component synthesis of 3,4-dihydropyrimidinones using MCM-41 anchored sulfonic acid （MCM-41-R-SO3H） as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.

Study on Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalytic Reaction (V) Screening Catalysts and Optimizing Synthesis Conditions

Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was Lao.szPbo.asMnOa and the average diameter could be about 25.4nm. The optimuna conditions for synthesis of DPC with Pd/LasPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catalyst/phenol mass ratio l to 50, pressure 4.5MPa, volume concentration of O2 25%, reaction temperature 60℃ and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.

Laboratory simulation of SO_2 heterogeneous reactions on hematite surface under different SO_2 concentrations

The variations of sulfate formation and optical coefficients during SO2 heterogeneous reactions on hematite surface under different SO2 concentrations were examined using in situ diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS） and ion chromatograph （IC）. Laboratory experiments revealed that within ambient SO2 of 0.51-18.6 ppmv, sulfate product, producing velocity, absorption and backward scattering coefficients showed an increasing trend with SO2 concentration. Under given SO2 concentration, the velocity of sulfate producing performed an evolution of initial increasing, midterm decreasing and final stabilizing. The reactive uptake and Brunaner-Emmett-Teller （BET） uptake coefficients of heterogeneous reactions rose with SOz and exhibited high reactivities. Considering global warming, this result is important for the knowledge of heterogeneous reactions of SO2 on mineral particle surface in the atmosphere and the assessment of their impacts on radiative forcing.

Melting heat transfer with radiative effects and homogeneous–heterogeneous reaction in thermally stratified stagnation flow embedded in porous medium

The present article deals with thermally stratified stagnation-point flow saturated in porous medium on surface of variable thickness along with more convincing and reliable surface condition termed as melting heat transfer.Homogeneous–heterogeneous reaction and radiative effects have been further taken into account to reconnoiterproperties of heat transfer.Melting heat transfer and phenomenon of homogeneous–heterogeneous reaction have engrossed widespread utilization in purification of metals,welding process,electroslag melting,biochemical systems,catalysis and several industrial developments.Suitable transformations are utilized to attain a scheme of ordinary differential equations possessing exceedingly nonlinear nature.Homotopic process is employed to develop convergent solutions of the resulting problem.Discussion regarding velocity,thermal field and concentration distribution for several involved parameters is pivotal part.Graphical behaviors of skin friction coefficient and Nusselt number are also portrayed.Concentration of the reactants is found to depreciate as a result of strength of both heterogeneous and homogeneous reaction parameters.With existence of melting phenomenon,declining attitude of fluid temperature is observed for higher radiation parameter.

Stabilization of heterogeneous hydrogenation catalysts for the aqueous-phase reactions of renewable feedstocks

The conversion of biomass-derived products to fine chemicals and fuels is extremely important for the utilization of renewable energy sources.Water is not only a by-product formed during the hydrogenation of biomass-derived oxygenated chemicals,but also an inexpensive and nontoxic solvent.The instability of solid catalysts for aqueous-phase reactions caused by metal leaching and the collapse of a catalyst support represents a significant challenge.In this work,various catalyst stabilization strategies including the nanospace and interfacial confinements that prevent sintering and leaching of metal nanoparticles as well as modification methods for increasing the support stability are summarized and systemically discussed.In addition,feasible approaches to designing stable and efficient heterogeneous catalysts for aqueous-phase reactions are proposed.

A modified model for isothermal homogeneous and heterogeneous reactions in the boundary-layer flow of a nanofluid

The homogeneous and heterogeneous reactions in the boundary-layer of a flat surface are considered. The autocatalysts are assumed to be of regular sizes, while the solution is a dilute nanofluid. The heat release due to the chemical reactions is taken into account. The Buongiorno’s model is used to describe the behaviors of this reaction system. This configuration makes the current model be different from all previous publications. Multiple solutions are given numerically to the rescaled nonlinear system, whose stability is verified. The results show that the strength coefficients of the homogeneous and heterogeneous reactions are key factors to cause the appearance of the multiple solutions in the distribution of the chemical reactions. Nanofluids enhance the diffusion of heat and help maintain the stability of chemical reactions.

Modeling Study of the Impact of Heterogeneous Reactions on Dust Surfaces on Aerosol Optical Depth and Direct Radiative Forcing over East Asia in Springtime

The spatial distributions and interannual variations of aerosol concentrations, aerosol optical depth （AOD）, aerosol direct radiative forcings, and their responses to heterogeneous reactions on dust surfaces over East Asia in March 2006-10 were investigated by utilizing a regional coupled climate-chemistry/aerosol model. Anthropogenic aerosol concentrations （inorganic ＋ carbonaceous） were higher in March 2006 and 2008, whereas soil dust reached its highest levels in March 2006 and 2010, resulting in stronger aerosol radiative forcings in these periods. The domain and five-year （2006-10） monthly mean concentrations of anthropogenic and dust aerosols, AOD, and radiative forcings at the surface （SURF） and at the top of the atmosphere （TOA） in March were 2.4 μg m 3 13.1 lag m^-3, 0.18, -19.0 W m^-2, and -7.4 W m^-2, respectively. Heterogeneous reactions led to an increase of total inorganic aerosol concentration; however, the ambient inorganic aerosol concentration decreased, resulting in a smaller AOD and weaker aerosol radiative forcings. In March 2006 and 2010, the changes in ambient inorganic aerosols, AOD, and aerosol radiative forcings were more evident. In terms of the domain and five-year averages, the total inorganic aerosol concentrations increased by 13.7% （0.17 μg m^-3） due to heterogeneous reactions, but the ambient inorganic aerosol concentrations were reduced by 10.5% （0.13 lag m-3）. As a result, the changes in AOD, SURF and TOA radiative forcings were estimated to be -3.9% （-0.007）, -1.7% （0.34 W m^-2）, and -4.3% （0.34 W m^-2）, respectively, in March over East Asia.

Heterogeneous Reactions between Starch and AKD under Solvent-free Conditions

Oxidized starch powder and cationic starch solution were reacted with alkyl ketene dimer(AKD) under heterogeneous conditions at 70℃ for 12 h.The AKD molecules reacted with starch hydroxyl groups to form β-keto ester linkages under the above conditions.The reaction products were separated into CHCl_3-soluble and CHCl_3-insoluble fractions.FT-IR spectroscopy,SEM,Xray diffraction,and TG-DTA analyses of the CHCl_3-insoluble fraction indicated that β-keto ester substituents were introduced to hydroxyl groups on the starch surfaces.The results indicated that hydrogen bonds between the starch molecules were disrupted under heterogeneous conditions upon heating.The activity and accessibility of hydroxyl groups were enhanced,as a result of which β-keto ester bonds were produced between AKD and starch.Based on these results,we speculate that the β-keto esters which existed in the sheets sized by AKD emulsions were generated by the reaction between AKD and starch.

Melting heat transfer in Cu-water and Ag-water nanofluids flow with homogeneous-heterogeneous reactions

This article addresses melting heat transfer in magnetohydrodynamics(MHD)nanofluid flows by a rotating disk. The analysis is performed in Cu-water and Ag-water nanofluids. Thermal radiation, viscous dissipation, and chemical reactions impacts are added in the nanofluid model. Appropriate transformations lead to the nondimensionalized boundary layer equations. Series solutions for the resulting equations are computed.The role of pertinent parameters on the velocity, temperature, and concentration is analyzed in the outputs. It is revealed that the larger melting parameter enhances the velocity profile while the temperature profile decreases. The surface drag force and heat transfer rate are computed under the influence of pertinent parameters. Furthermore, the homogeneous reaction parameter serves to decrease the surface concentration.

Reaction Kinetics for Heterogeneous Oxidation of Mn(III) ～Toluene

The reaction kinetics of the heterogeneous oxidation of toluene with Mn 3+ was studied by considering the effects of disproportionation of Mn 3+ in reaction system, a 'parallel' modulus was set up. And then the concentration of Mn 3+ in disproportionation and the concentration of benzaldehyde in oxidation were respectively determined in turn, the rate constant, order and pseudo activation energy of the heterogeneous oxidation were obtained by mathematical deduction and the kinetic equation was concluded. In addition, the reaction mechanism was analyzed. It shows that the results are completely consistent with modulus.

Theoretical and Experimental Study of Reaction of Transesterification of Vegetable Oils in an Alcohol Environment in the SbCF and SCF Conditions with the Ultrasonic Emulsification of Reaction Mixture and the Use of Heterogeneous Catalysts

A quantum-chemical study of the mechanism of transesterification reaction carried out in the traditional and supercritical fluid (SCF) conditions has been performed. Samples of biodiesel fuel have been derived from rapeseed oil in the environment of supercritical ethanol using a flow type unit, both in the absence and in the presence of heterogeneous catalysts-metal oxides. Experimental studies of kinematic viscosity of a large array of samples of derived biodiesel have been performed. The viscous correlation allowing determining the content of the desired product-fatty acid ethyl esters (FAEE)-in biodiesel samples, has been made based on the obtained experimental data on the kinematic viscosity of biodiesel samples. The influence of change of the dielectric permittivity of working environments on the rate of reaction of transesterification in the supercritical fluid conditions has been revealed.

Note on characteristics of homogeneous-heterogeneous reaction in flow of Jeffrey fluid

This letter describes the characteristics of homogeneous-heterogeneous re- action in the boundary layer flow of a Jeffrey fluid due to an impermeable horizontal stretching sheet. An analysis is carried out through the similar values of reactant and auto catalyst diffusion coefficients. Heat released by the reaction is not accounted. The exact solution for the flow of the Jeffrey fluid is constructed. The series solution for the concentration equation is derived. The velocity and concentration fields reflecting the impact of interesting parameters are plotted and examined.

Simultaneous Bulk-and Surface-initiated Living Polymerization Studied with a Heterogeneous Stochastic Reaction Model

To better characterize the properties of surface-initiated polymers, simultaneous bulk-and surface-initiated polymerizations are usually carried out by assuming that the properties of the surface-initiated polymers resemble those of the bulk-initiated polymers. Through a Monte Carlo simulation using a heterogeneous stochastic reaction model, it was discovered that the bulk-initiated polymers exhibit a higher molecular weight and a lower dispersity than the corresponding surface-initiated polymers, which indicates that the equivalent assumption is invalid. Furthermore, the molecular weight distributions of the two types of polymers are also different, suggesting different polymerization mechanisms. The results can be simply explained by the heterogeneous distributions of reactants in the system. This study is helpful to better understand surface-initiated polymerization.

Application of metal-based catalysts for Fenton reaction: from homogeneous to heterogeneous, from nanocrystals to single atom

Nowadays, increasing emissions of hazardous chemicals cause serious environmental pollution. The advanced oxidation processes (AOPs), which produce numbers of reactive oxygen species (ROS), are one of the most widely used technologies for degrading refractory pollutants in aqueous phase. Among these, Fenton reaction including both homogeneous and heterogeneous processes, has received increasing attention for water treatment. In this review, various nanomaterials with different size such as nanocrystals, nanoparticles (e.g., iron-based minerals, bimetallic oxides, zero-valent iron, quantum dots) and metal-based single atom catalysts (SACs) applied in homogeneous and heterogeneous Fenton reactions, as well as the corresponding catalytic mechanisms will be systematically summarized. Several factors including the morphology, chemical composition, geometric/electronic structures influence the catalytical behavior simultaneously. Here, the recent research advancement including the advantages and further challenges in homogeneous and heterogeneous Fenton system will be introduced in detail. Furthermore, developments for different nanomaterials, from nanocrystals, nanoparticles (minerals, bimetallic oxides represented by Fe-based catalysts, and nanosized zero valent iron materials) to SACs will be discussed. Some representative catalysts for Fenton reaction and their applications will be presented. In addition, commonly-used supports (e.g., graphene oxide, g-C3N4, and carbon nanotubes) and metal-organic frameworks (MOFs)/derivatives and metal-support interaction for improving Fenton-like performance will be introduced. Finally, different types of catalysts for Fenton reaction are compared and their practical application and operational costs are summarized.

Regulating Oxygen Vacancy Defects in Heterogeneous NiO-CeO_(2)−δ Hollow Multi-shelled Structure for Boosting Oxygen Evolution Reaction

CeO_(2) with excellent oxygen storage-exchange capacity and NiO with excellent surface activity were used to construct a heterogeneous NiO-CeO_(2)−δhollow multi-shelled structure(HoMS)by spray drying.It turned out that as the proportion of CeO_(2) increases,the overpotential and Tafel slope of NiO-CeO_(2)−δHoMSs first decreased and then increased.This is mainly because the construction of the NiO-CeO_(2)−δHoMSs not only increases the specific surface area,but also introduces oxygen vacancy defects,thus improving the interface charge transfer capability of the materials and further improving the oxygen evolution reaction(OER)performance.However,the increase of the calcination temperature will induce the decay of the OER performance of NiO-CeO_(2)−δHoMSs,which is mainly due to the decrease of the specific surface area,the reduction of oxygen vacancy defects,and the weakening of interface charge transfer capability.Furthermore,a series of heterogeneous composite HoMSs,such as Ni/Co,Mo/Ni,Al/Ni and Fe/Ni oxides was successfully constructed by spray drying,which enriched the diversity of HoMSs.

Reinterpret the heterogeneous reaction of α-Fe_(2)O_(3) and NO_(2) with 2D-COS:The role of SDS,UV and SO_(2)

Heterogeneous reaction of mineral aerosols and atmospheric polluting gases play an important role in atmospheric chemistry.In this study,the reactions of NO_(2) with or without SO_(2) mixture gas on the surface of α-Fe_(2)O_(3) particles under dry conditions were studied.The effects of sodium dodecyl sulfate(SDS)and the heterogeneous reaction under both dark and UV irradiation conditions were investigated.The infrared spectrum analyzed by the two-dimensional correlation spectroscopy(2D-COS)was used to obtain the products formation sequences.The results showed that UV irradiation can promote the production of nitrate.The 2D-COS analysis indicated SDS changed the sequence order of nitrate and nitrite species during reactions.In oxidation conditions,the final product of heterogeneous reaction of NO_(2) and α-Fe_(2)O_(3) was monodentate nitrate.Only the heterogenous reaction of NO_(2) and α-Fe_(2)O_(3) containing SDS(FOS)without UV light,the final product was bidentate nitrate.SDS was the catalysis agent supply and photoresist to the system.With surface active compounds,the environmental lifetime of heterogeneous reactions between trace gases and aerosols extends.Surfactants,ultraviolet light,and the types of gases involved in the reaction all have complex effects on the aerosol aging process.This study provided a reference for subsequent heterogeneous reaction studies and the formation of aerosols.