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Zr-Modified SAPO-34 zeolites with hierarchical porous structure were synthesized in the presence of UiO-66. The Zr0.50-SAPO-34 zeolites exhibited long lifetimes (>1500 min) and excellent selectivity for light olefins (98.66%) in the MTO reaction.

H-ZSM-5 zeolites are successfully synthesized within 1 h with an organic template free system by the seed-assisted method. The synthetic method not only reduces the production cost of H-ZSM-5 zeolite, but also decreases the environmental pollution produced compared with that of the conventional synthesis process. Characterization by SEM, XRD, N2 adsorption–desorption, NH3-TPD, and Py-IR confirms that the H-ZSM-5 product has a high crystallinity and reveals that the rapid synthesis process is in accordance with the seed surface crystallization mechanism. To improve the aromatic selectivity on the H-ZSM-5 zeolite, different concentrations of Mo and Zn catalysts were prepared by incipient wetness impregnation and the ion-exchange method. Mo-Zn/H-ZSM-5-SAS-1 h have similar catalytic lifetimes and higher selectivity of paraxylene in aromatic products compared with Mo-Zn/H-ZSM-5-seed in the reaction of methanol to aromatic. However, the catalytic lifetime of 6%Mo/H-ZSM-5-SAS-1 h is shorter than that of the 6%Mo/H-ZSM-5-seed catalyst in methane to benzene reaction under the same reaction conditions.

The dramatic increase in atmospheric CO2 concentrations has attracted people’s attention, and many strategies have been developed to convert CO2 into high-value chemicals. Metal-organic frameworks (MOFs), as a class of versatile materials, can be used in the CO2 capture and conversion because of their unique porosity, large specific surface area, rich pore structure, multiple active centers, good stability and recyclability. Various functional nanomaterials have been designed and synthesized based on metal organic framework (MOF) of crystalline porous materials to meet these challenges. Herein, in this review, the latest processes of MOFs in field the of CO2 hydrogenation to carbon monoxide, methane, formic acid, methanol and olefins are summarized, and the synthesis methods of catalysts based on MOFs and the reasons for their high catalytic activity are analyzed. Besides, a brief introduction to improve the catalytic activity of the new MOF material and explore the feasible strategies for CO2 conversion are advised. Finally, the paper discusses the main challenges and opportunities of MOF-type catalysts in CO2 chemical conversion, and presents a brief outlook on further developments in this research area.

Directly incorporated phosphorus species into the framework of HZSM-5 zeolite (H[P, Al]-ZSM-5) was successfully synthesized by the facile hydrothermal method. It was characterized by employing XRD, ICP-OES, SEM, FT-IR, N2 adsorption-desorption, NH3-TPD, XPS and TG-DTA, respectively. The effects of the phosphorus species content, temperature, WHSV, and the molar ratio of methanol/1-butene in coupling transformation of methanol with 1-butene to propylene catalyzed by H[P, Al]-ZSM-5 in a fixed bed reactor were studied systematically. Tests have suggested the acid content and specific surface area of H[P, Al]-ZSM-5 are reduced. Under the condition of reaction temperature at 550�Z, molar ratio of methanol/1-butene to 1.0, reaction pressure at 0.1 MPa and WHSV= 3.53 h-1, the P-modified HZSM-5 zeolite (with the P2O5 molar composition of 0.4 )the selectivity and yield of propylene are 35.6% and 32.5%, respectively.

Nanoscale polymer spherical and hollow structure HZSM-5 zeolites are prepared by hydrothermal and desilication–recrystallization methods. In addition, the crystallite size of two types of HZSM-5 can be easily controlled by changing H2O/Si mole ratio. The hollow structure HZSM-5 zeolite is formed, it is due to the 010 crystal plane is the most energetically favorable orientation in silicalite-1 and the Si species is first removed on this crystal plane. The properties of different morphology zeolites were characterized by means of XRD, SEM, TEM, NH3-TPD, N2 isothermal adsorption–desorption and TG, and the catalytic performance of these two types of HZSM-5 in MTA reaction was investigated in a fixed-bed differential reactor. The results showed that the multilevel pore structure and suitable acid strength and more acid density were obtained in the hollow structure HZSM-5 zeolite. Therefore, the hollow HZSM-5 zeolite exhibited that higher catalytic lifetime and selectivity of aromatics than nanoscale polymer spherical HZSM-5 zeolite in MTA reaction. Furthermore, the Al distribution on the 010 crystal plane may change slightly during the process of fabricating hollow mesoporous, which leads to higher selectivity of p-xylene over hollow HZSM-5 than nanoscale polymer spherical HZSM-5 zeolite.

The ZnIn/HZSM-5 catalyst was prepared by the wetness impregnation method, and the structure of catalyst was characterized by XRD, SEM, TEM, H2-TPR, NH3-TPD, XPS, TG, and N2 adsorption–desorption and then investigated in the coupling of propane with CO2 to propylene. It is found that the addition of Zn species is beneficial to the dispersion of In2O3 over HZSM-5, which plays an important role in propene formation, and adjusts the acidity distribution of In/HZSM-5 catalyst, as well as significantly improves the activity of In/HZSM-5 catalyst. The selectivity of propylene is 68.21% in the coupling of propane with CO2 over ZnIn/HZSM-5 catalyst when the time on stream (TOS) is 2 h, reaction temperature is 580 °C, reaction pressure is 0.3 MPa, C3H6:CO2:N2 = 1:4:5, catalyst mass is 0.2 g, and space velocity is 6000 mL gcat−1 h−1. However, the selectivity of propylene is only 63.33% and 0.25% in the propane dehydrogenation or CO2 hydrogenation reaction, respectively. The ZnIn/HZSM-5 catalyst showed a higher stability with only 0.80% conversion drop after three cycles.

To improve the dispersion of metals and to enhance the catalytic performance of SAPO-34 molecular sieves, the template-assisted method was applied to synthesize Co, Ni and Zn modified SAPO-34 molecular sieves by using palygorskite as silicon source and tetraethylammonium hydroxide as template. The metal modified SAPO-34 molecular sieves were characterized by XRD, SEM, XPS, N2-adsorption-desorption, NH3-TPD, FTIR, ICP-AES and TG. The N atoms of tetraethylammonium hydroxide exhibited the different forces to three metal ions, thus the acidity of the molecular sieves was further regulated. Compared with metal modified SAPO-34 molecular sieves prepared by impregnation, metal modified SAPO-34 molecular sieves prepared by template-assisted maintained higher surface area, bigger pore volume and better dispersion of metals. The catalytic performance of metal modified SAPO-34 molecular sieves prepared by template-assisted method in the reaction of methanol-to-olefins (MTO) was investigated in the fixed bed reactor. Under the reaction conditions that the reaction temperature was 400 °C, the reaction pressure was 0.1 MPa, the feed WHSV was 2.0 h−1 and the mass of catalyst was 0.5 g, Ni modified SAPO-34 molecular sieves exhibited great methanol conversion and high selectivity to light olefins. The selectivity of light olefins reached 95.7%.

Propane dehydrogenation to propene is an endothermic reaction and CO2 hydrogenation to light olefins is an exothermic reaction. Using the CO2 hydrogenation reaction to consume the hydrogen from the propane dehydrogenation reaction, which is more favorable to propylene formation. A new method for coupling propane and CO2 to propylene is presented. The V–Fe modified KIT-6 was prepared by the ultrasonic-assisted impregnation method and used for coupling reaction of propane with CO2 to propylene. Exploring the relationship between catalytic properties and physicochemical characteristics through several characterization methods. As the appropriate amounts of V and Fe species were introduced into the framework of KIT-6, V–Fe modified KIT-6 performed large specific surface area, a highly ordered mesoporous structure and highly dispersed V and Fe active sites. The catalysis performance of V–Fe modified KIT-6 zeolites for production of propylene by propane dehydrogenation, CO2 hydrogenation and coupling reaction of C3H8 with CO2 was compared. Under the conditions of C3H8/CO2/N2 = 1:4:5, total flow rate = 20 mL/min, the temperature at 580 °C, the reaction pressure at 0.1 MPa, V/Fe molar ratio = 2 and the catalyst mass of 0.2 g, the propane conversion, propylene selectivity and yield are 37.8%, 87.0% and 32.9%, respectively.

Phosphorus promoted HZSM-5 zeolites (P-HZSM-5) were prepared by synthetic methods of incipient wetness impregnation and in situ synthesis, respectively. This was characterized by the means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller method (BET), thermogravimetry (TG), and NH3-TPD. The P-HZSM-5 zeolite prepared by incipient wetness impregnation has a large specific surface area and pore size, and the weak acidity is remarkably increased. The catalytic activity of P-HZSM-5 for the coupling transformation of methanol with 1-butene to propylene was investigated. Under the reaction conditions of temperature at 550 °C, pressure at 0.4 MPa, space velocity at 1800 mL/(gcat h), and mole ratio of CH3OH/C4H8 at 1:1, the conversion of C4H8 can reach to 75.8%, and the selectivity and yield of propylene are 42.2% and 31.9%, respectively.

CO2 hydrogenation to light olefins is an exothermic reaction, while propane dehydrogenation to propylene is an endothermic reaction, and with generating of hydrogen. Coupling of the two reactions can break the equilibrium limit of thermodynamics and dynamics of the single reaction and improve yield of propylene. Therefore, the effects of different crystalline zeolites (HZSM-5, SAPO-34 and Al-SBA-16) on the reactivity of propane coupled with CO2 to propylene were investigated. The properties of different zeolites were characterized by means of XRD, SEM, NH3-TPD, N2 desorption and TG, and the catalytic performance of the three different zeolites in the reaction of propane and carbon dioxide coupling to propylene was investigated in a fixed bed reactor. The experimental results showed that HZSM-5 zeolite had high content of weak acid, large specific surface area and excellent catalytic activity. Typically the propane conversion rate is 10.5%, the CO2 conversion is 3.0%, the propylene selectivity is 38.4% and the yield is 4.0% when the volume ratio of propane to CO2 is 1:4, the reaction pressure is 0.1 MPa, the reaction temperature is 580°C, the catalyst mass is 0.2 g and the space velocity is 6000 mL/(gcat·h).

S-doped NiFe-based particles were prepared by a solvothermal method and used to degrade methylene blue (MB) aqueous solutions with visible light in a heterogeneous Fenton reaction. The obtained solid samples were characterized by XRD, SEM, TEM, and XPS. It was found that 0.2 g L−1 NiFe2S4 can degrade 99.8% MB solution within 6 min in the presence of 5 mM H2O2 and natural pH. The recycle experiments results indicate that the NiFe2S4 catalyst possessed better stability than NiFe2O4. Furthermore, NiFe2S4 particles can be easily separated from contaminant solution by using a magnet due to their excellent ferromagnetism. COD analysis experiments indicated that the COD removal rate of NiFe2S4 is 73.1% in 30 min. A possible mechanism was proposed, and the degradation products were measured by LC-MS.

The CuO–La2O3/ZrO2 catalysts calcined at different temperatures from 500 to 800 °C were studied for the hydrogenation of oxalates to ethylene glycol (EG). Along with the increase of calcination temperatures, the BET surface area, pore volume, and Cu dispersion decreased, whereas the crystallite sizes of Cu species increased. Interestingly, the superior performance such as a 98% selectivity of EG in dimethyl oxalate hydrogenation or a 96.5% selectivity of EG in diethyl oxalate hydrogenation was obtained over the catalyst calcined at 700 °C. Essentially, the surface synergism between Cu species and monoclinic ZrO2 was enhanced by the higher calcination temperature, resulting in the remarkable surface adsorption and activation of H2. Besides, the increase of calcination temperature significantly reduced the surface acidity and basicity, which could effectively suppress the byproduct formation.

Right here, flower-like FeMoO

Using ethylene glycol as solvent and PVP as structure-directing agent, CuFe2O4 nanospheres were successfully prepared by solvothermal method. The crystal structure, morphology, magnetic properties, and pore-size distribution of samples were characterized by using X-ray diffraction, scanning electron microscope, transmission electron microscope, VSM, and BET, respectively. The effects of various preparation factors on the crystal form and morphology of the obtained samples were systematically discussed. The result exhibited that the self-assembled hollow nanospheres with good crystal form and morphology are obtained under the conditions of 0.50 g PVP, 9 mmol NaAc, reaction temperature of 180 °C, and reaction time of 24 h. The catalytic activity of CuFe2O4 hollow nanospheres was evaluated by the degradation of methylene blue (MB) and the possible degradation mechanism and pathway of MB in the CuFe2O4/H2O2 photo-Fenton-like system were proposed. In addition, the properties of CuFe2O4 particles prepared by different methods were compared and analyzed. The sample synthesized by solvothermal method has a large specific surface area and excellent magnetic properties. Furthermore, the increase in the photoelectric response and the conductivity are beneficial to the improvement of catalytic performance.

Homogeneous hollow CuO–ZnO–Al2O3 microspheres, which were synthesised, used carbonaceous saccharide as a template by the hydrothermal treatment at 180°C. The hollow microspheres structure of composite metal oxides was characterised by the methods of X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and N2 adsorption–desorption isothermal. In the evaluation of the hydrogenation of carbon dioxide, the synthesised hollow CuO/ZnO/Al2O3 composite microspheres exhibited higher selectivity and yield of methanol than CuO/ZnO/Al2O3 prepared by a co-precipitation method. An optimum yield of methanol of 15.3% with the 24.7% CO2 per pass conversion was obtained under the reaction conditions of pressure at 3.0 MPa, space velocity at 1800 ml gcat −1 h−1, the volume ratio of CO2/H2 at 1:3 and temperature at 262°C.

To understand the relationship between the catalytic performance, crystallite size, and acidity of SAPO-34 zeolites better, a series of SAPO-34 zeolites were prepared by hydrothermal crystallization using palygorskite as silicon and partial aluminum source, and selecting two kinds of triethylamine, morpholine and tetraethylammonium hydroxide as dual templates. The obtained SAPO-34 zeolites were characterized via the methods of XRD, SEM, N2-adsorption–desorption, NH3-TPD, FTIR, XRF, 29Si MAS NMR, 27Al MAS NMR and TG. The properties of the templates affected the crystal growth rate that triethylamine and morpholine can cause a larger crystallite size while tetraethylammonium hydroxide can form small crystallite size particles. The number of acid sites of SAPO-34 zeolites first decreased and then increased with the increase of morpholine. The formation of Si islands can enhance the number of acid sites of SAPO-34 zeolites. The catalytic performance of SAPO-34 zeolites in methanol-to-olefins (MTO) reaction was investigated in a fixed bed reactor. Under reaction conditions, when the reaction temperature was 400 °C, the feed WHSV was 2.0 h−1, the mass of the catalyst was 0.5 g, at atmospheric pressure, the sample with an amount of acid sites of 0.85 mmol g−1 and crystallite size of 0.84 μm exhibited the optimum catalytic performance with methanol conversion at 100%, light olefin selectivity at 97.15% and catalytic lifetime at more than 1050 min.

Methanol to aromatics (MTA) is an effective way to produce aromatics by non-petroleum route. The acidity and structure of zeolite catalysts are the key to aromatics yield and stability of catalysts in MTA reaction. Here, Zn-modified HZSM-5 catalysts were prepared by physical mixing method (PM), in-situ hydrothermal synthesis method (SH) and steam-assisted crystallization method (SAC) using ZIF-8 as sacrificial template and Zn source. XRD, SEM, TEM, N2 adsorption-desorption, ICP-OES, NH3-TPD, Py-IR, XPS, H2-TPR, TG characterization methods were used to investigate the physical and chemical properties of the catalysts. The influence of preparation methods of catalysts, the addition amount of ZIF-8, different Zn sources and reaction conditions on the products distribution in MTA reaction were investigated. The results showed that the crystallinity of ZnZ8(SAC)/Z5 catalyst was improved and the hierarchical pore structure was obtained successfully after introduced ZIF-8 by steam-assisted crystallization method. Among them, ZnZ8 mainly exists as ZnOH+ species, which improved the utilization rate of Zn atoms and more L acid sites and moderate acid concentration were formed. The addition amount of ZIF-8 can affect the crystalline size, pore structure and the concentration of ZnOH+ species of ZnZ8(SAC)/Z5. An appropriate ratio of B/L acid concentration was formed when adding an appropriate amount of ZIF-8. Compared with the traditional Z5 catalyst modified with Zn(NO3)2 as Zn source (1% ZnZN(SAC)/Z5), there are smaller particle size, larger specific surface area and mesopore volume as well as suitable acid distribution in 1% ZnZ8(SAC)/Z5 catalyst. The preparation method of catalyst, the addition amount of ZIF-8, different Zn sources and reaction conditions have a significant effect on the selectivity of BTX.

It is a challenge to develop heterogeneous Fenton-like catalysts with excellent performance and stability in the field of wastewater treatment. In this work, the FeS2-Fe1-xS heterostructure catalyst was prepared by solvothermal method through adding cobalt element to change the particle nucleation process and inhibit the transformation process of pyrrhotite (Fe1-xS) phase to pyrite (FeS2) phase. Then, a series of experiments were devised to clarify the catalytic activity of FeS2-Fe1-xS heterostructure. The degradation experiments exhibited that 99.9% degradation efficiency was achieved for 30 mg/L orange II solution within 15 min at the conditions of 0.2 g/L FeS2-Fe1-xS, 2 mM H2O2 and pH = 3.0. In addition, the reusability of the FeS2-Fe1-xS catalyst was also investigated and the result displayed that degradation efficiency of orange II can reach 95.2% after eight cycles. The degradation of orange II was enhanced by Fenton reaction between FeS2-Fe1-xS and dissolved oxygen, which could smoothly release Fe2+ and Fe3+ for the activation of H2O2 to produce more hydroxyl radicals. Finally, the degradation pathway of orange II was proposed by detecting intermediates produced in FeS2-Fe1-xS/H2O2 photo-Fenton-like system by liquid chromatography-mass spectrometry (LC-MS). In short, FeS2-Fe1-xS is a promising catalyst for removing the organic pollutants from solutions.

A facile approach was developed for the preparation of nano-sized HZSM-5 with a hierarchical mesoporous structure by adding imidazole into conventional zeolite synthesis precursor solution. The physicochemical properties of modified HZSM-5 were characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), NH3-temperature-programmed desorption (NH3-TPD) and pyridine adsorption infrared spectroscopy (Py-IR). The coke in spent catalysts was characterized by thermogravimetry (TG). The results showed that hierarchical HZSM-5 zeolites with excellent textural properties, such as abundant porous structure, uniform particle size and suitable acidity, could be synthesized by the recipe of one-pot synthesis routes. Moreover, the obtained HZSM-5 exhibited higher selectivity of total aromatics as well as longer lifetime in the catalytic conversion of methanol to aromatics, comparing with conventional HZSM-5. It is expected that the synthesis approach demonstrated here will be applicable to other zeolites with particular textural properties and controllable particle sizes, facilitating the emergence of new-type porous materials and their related applications in catalysis and separation.

Elemental doping has been proven to be an effective strategy for increasing the catalytic activity and structural stability of Fenton catalysts. Therefore, this work reports that Mn-doped FeS

Hematite (α-Fe2O3), as one of Fenton reagents, is widely investigated for the treatment of wastewater in the field of advanced oxidation processes (AOPs). Considering the fast charge carrier recombination of hematite (α-Fe2O3), we have successfully synthesized a novel and high active heterogeneous Fenton catalyst α-Fe2O3/Cu2O(SO4) for the degradation of organic pollutants. The results show that the as-obtained Cu2O(SO4)-Fe9 composite exhibits excellent degradation properties of Orange II. 98.9% degradation rate was achieved for 100 mL of 50 mg/L Orange II solution in the condition of 0.3 g/L Cu2O(SO4)-Fe9 catalyst, 3 mM H2O2 and pH = 3.5. The degradation rate constants of Cu2O(SO4)-Fe9 in the photo-Fenton-like system are 9.33 and 4.07 times of Cu2O(SO4) and α-Fe2O3, respectively. In addition, the mechanism and pathway for the degradation of Orange II were proposed. The scheme of combining copper-based oxysulfate Cu2O(SO4) with hematite (α-Fe2O3) could improve the efficiency of charge carrier separation, which will further enhance the catalytic activity and expand its application in water purification.

Palygorskite was used as a silicon and partial aluminum source to prepare SAPO-34 molecular sieves using diethylamine, triethylamine, morpholine and tetraethylammonium hydroxide as templates. The synthesized SAPO-34 molecular sieves were characterized by using the methods of XRD, SEM, EDS, BET, FT-IR, NH3-TPD, H2-TPR and TG. Composite catalysts of CuO-ZnO-Al2O3/SAPO-34 were prepared by mechanically mixing SAPO-34 molecular sieves with CuO-ZnO-Al2O3 and were used in the direct synthesis of light olefins via CO2 hydrogenation. The results showed that SAPO-34 molecular sieves prepared by acid-treated palygorskite using tetraethylammonium hydroxide as a template had a higher specific surface area, a greater CO2 conversion rate and higher light olefin selectivity. The CO2 conversion rate reached 53.5%, the light olefin selectivity reached 62.1%, and the yield reached 33.2% when the reaction conditions were as follows: reaction temperature 673 K, reaction pressure 3.0 MPa, volume ratio of CO2/H2 1:3 and 0.5 g composite catalyst.

Elemental doping has been proven to be an effective strategy for increasing the catalytic activity and structural stability of Fenton catalysts. Therefore, this work reports that Mn-doped FeS2/Fe2O3 (Mn3O4–FeS2/Fe2O3) has excellent catalytic performance for the degradation of Orange II under simulated solar energy. Degradation experiment results showed that the sample with a manganese-iron molar ratio of 1:2 exhibited higher activity than others. The degradation rate of 20 mg/L OII reached 99.0% in 18 min under the conditions of 0.3 g/L Mn3O4–FeS2/Fe2O3, 5 mM H2O2 and pH = 2.8. In addition to, the Mn3O4–FeS2/Fe2O3 catalyst shows good reusability for Orange II and high activity for other dyes (MB, MG, Rh B and MO) under optimal conditions. Degradation mechanism study indicated that the heterogeneous Fenton reaction was promoted by retarding the recombination of photogenerated charge carriers and accelerating the cycle between Fe3+/Mn2+ and Fe2+/Mn3+, which improved photo-Fenton-like catalytic performance, resulting in the enhanced degradation of organic pollutant. Finally, a possible degradation pathway was proposed according to the results of liquid chromatography-mass spectrometry (LC-MS). In short, the catalyst has potential application value in wastewater treatment.

Spherical carbons were prepared successfully from aqueous glucose using hydrothermal method. After covered with aqueous Cu 2+ , Zn 2+ and Al 3+ ions during the co-precipitation treatment, carbons were removed via calcination to yield CuO–ZnO–Al 2 O 3 nanoparticles. HZSM-5 membrane, which was synthesized using tetrapropylammonium hydroxide as templating agent, was packed onto CuO–ZnO–Al 2 O 3 nanoparticles hydrothermally to form HZSM-5 packed CuO–ZnO–Al 2 O 3 nanoparticles. It was characterized by the method of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen sorption measurement. HZSM-5 packed CuO–ZnO–Al 2 O 3 nanoparticles were used as catalysts for the CO 2 hydrogenation to dimethyl ether. The catalyst activity was investigated in a fixed-bed reactor. Under the reaction conditions of pressure at 3.0 MPa, space velocity (SV) of 1800 mL g cat −1 h −1 , volume ratio of CO 2 /H 2 to 1:3 and temperature at 270 °C, the conversion of CO 2 could reach to 48.3%, with a dimethyl ether yield and selectivity of 23.4% and 48.5%, respectively.

The mixed acid of H2SO4/HNO3-pretreated multi-walled carbon nanotubes was employed as supports and ultrasound-assisted co-precipitation method was designed to prepare multi-walled carbon nanotubes supported CuO–ZnO–Al2O3/HZSM-5 catalyst. The catalyst was characterized by means of X-ray diffraction spectrum (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermal analysis (TG) and Brunauer–Emmett–Teller (BET). The catalyst activity for the preparation of dimethyl ether from hydrogenation of CO2 was investigated in a fixed-bed reactor, which showed that multi-walled carbon nanotubes could promote the catalyst activity of CuO–ZnO–Al2O3/HZSM-5. Under the reaction conditions of temperature at 262 °C, pressure at 3.0 MPa, H2/CO2 = 3 (volume ratio) and space velocity (SV) = 1800 mL gcat−1 h−1, the conversion per pass of carbon dioxide was 46.2%, with the dimethyl ether yield and selectivity of 20.9% and 45.2%.

AgBr sonocatalysts were prepared by a simple method. The AgBr sonocatalysts exhibited excellent sonocatalytic activities against the decolorization of methylene blue, rhodamine B, and methyl orange. By determining the content of OH radicals in the ultrasonic degradation of organic dyes, many OH radicals were detected, which may be responsible for the high sonodegradation rate over AgBr under ultrasonic radiation. Based on the effects of the initial dye concentration on the sonodegradation, we also discussed and analyzed the kinetic data, and the results are consistent with the first-order kinetic rate equation.

A new catalyst of silver tyipolyphosphate (Ag5P3O10) for sonodegradation of dyes, was prepared by a hydrothermal route. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–vis absorption spectroscopy (UV–vis), photoluminescence spectra (PL) and N2 adsorption–desorption methods. The degradation of dyes in water was investigated under ultrasonic irradiation in the presence of Ag5P3O10. The result shows Ag5P3O10 has the excellent sonodegradation activity of dyes. A large number of hydroxyl ( OH) radicals formed under ultrasonic radiation, and the content of OH radicals increased with increased radiation time. This phenomenon provided the main basis for the high sonodegradation activity of Ag5P3O10 under ultrasonic radiation. The kinetic model and its parameters were also discussed in detail.

The reaction of alcohols and carboxylic acids catalyzed by acids is the traditional method used to prepare esters in the chemical industry. In this study, we report the synthesis of active graphitic carbon nitride (g-C3N4) that may be used in the one-step reaction between benzaldehyde and alcohol to promote the selective formation of esters under visible light irradiation. Compared with the reaction carried out without illumination, g-C3N4 showed obvious improvements in ester formation. The presence of tin dioxide can also contribute to the formation of esters under visible light irradiation. The use of g-C3N4 for the esterification of various alcohols was explored, and the catalyst showed promising results.