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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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Catalytic performance is influenced by the morphology and assembly of catalyst particles. Therefore, Zn ion‐doped HZSM‐5 zeolite with different morphological structures is prepared using post‐treatments of selective dissolution and recrystallization, causing silicon components to migrate from the interior to the exterior in the different template etching processes. The core–shell, hollow, and hierarchical core–shell Zn/HZSM‐5 microspheres with weak acid sites on the external surfaces are successfully synthesized. Hierarchical core–shell‐structured Zn/HZSM‐5 microspheres with a silicon‐rich surface layer are prepared using an etching method in n‐butylamine solution. Their catalytic activity is investigated in methanol aromatization. The functionalized morphological Zn/HZSM‐5 catalysts show good catalytic performance and the silicon‐rich surface layer improves selectivity of p‐xylene in the reaction of methanol to aromatics. Three morphological structured zeolite synthesis routes for p‐xylene are reported and selectivity is studied. Zn/HZSM‐5Si shows lower activity in the conversion of methanol to aromatics, but higher selectivity to xylene (particularly p‐xylene) considering benzene, toluene, and xylene. The Zn/HZSM‐5 catalysts treated in tetrapropylammonium hydroxide (TAPOH) and n‐butylamine solution exhibit excellent catalytic activity and stability in MTA reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption energies of CO 2 on the surface oxygen vacancies of different crystalline In 2 O 3 were calculated using DFT. • The effect of the spatial distributions of two active components on the CO 2 hydrogenation to aromatics was studied. • The acidity of catalyst under different spatial distributions was studied through NH 3 -TPD. In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO 2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as "the closer, the better". However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In 2 O 3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO 2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO 2 by oxygen vacancy on c-In 2 O 3 (1 1 1) and h-In 2 O 3 (1 0 4) planes, it was found that O v1 on c-In 2 O 3 (1 1 1) and O v4 on h-In 2 O 3 (1 0 4) had the strongest adsorption energy for CO 2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO 2 conversion and aromatic selectivity are decreased. [ABSTRACT FROM AUTHOR]

In this study, the α-Fe 2 O 3 /MIL-53(Fe) composite was successfully designed and developed through a solvothermal method as a photo-Fenton catalyst and for the degradation of tetracycline hydrochloride (TC-HCl). The results show that the prepared composite exhibits superb performance for the degradation of TC-HCl ascribing to the synergistic effect between MIL-53(Fe) and α-Fe 2 O 3. And the formation of heterojunction structure is beneficial to reducing the band gap, enhancing the absorption of visible light, and improving the separation and transportation of photo-induced carriers. Moreover, this heterojunction structure can be formed without annealing treatment. The effects of pH, H 2 O 2 consumption and catalyst dosage on the degradation of TC-HCl are also investigated. The optimum conditions for target pollutant degradation were investigated according to the response surface methodology (RSM) result based on a central composite design (CCD). A possible mechanism of degradation of TC-HCl is proposed according to the main active radical that existed in the reaction process. This work provides a novelty perspective and in-depth and independent insight for the photo-Fenton mechanism of heterojunction structure modified MOFs material. [Display omitted] [ABSTRACT FROM AUTHOR]

We prepared ZnZr 7 O/HZ-1.5NH 4 F tandem catalyst with high catalytic activity for the direct conversion of CO 2 hydrogenation to aromatics by combining theoretical calculations and experiments. [Display omitted] • It was simulated that the (0 1 0) plane of the sheet HZSM-5 had the strongest adsorption capacity for CH 3 O* and CHOO*. • We prepared catalysts with high catalytic activity and stability by combining theoretical calculations and experiments. • The thickness can be precisely adjusted to prepare a series of sheet HZSM-5 by adding urea and NH 4 F. • Urea inhibits the generation of defective sites in HZSM-5, while NH 4 F promotes the generation of defective sites. • The thickness of the sheet HZSM-5 is also a factor affecting the catalytic activity. The adsorption properties of CH 3 O* and CHOO* adsorbed on the three crystal planes (0 0 1, 0 1 0, 1 0 1) of HZSM-5 were simulated by the generalized gradient approximation (GGA) of density functional theory (DFT), it was found that the (0 1 0) plane corresponding to the b-axis of the sheet HZSM-5 had the strongest adsorption energy for CH 3 O* and CHOO*. Therefore, we successfully synthesized sheet HZSM-5 with different thicknesses by adding the inhibitor (urea) and mineralizer (F−) to the synthesis system based on the theoretical calculations. The physicochemical properties of HZSM-5 were investigated by the characterization methods of SEM, TEM, Py-IR, OH-IR, CO 2 -TPD and so on. The results showed the thickness of HZSM-5 can be precisely adjusted by adding urea and NH 4 F and changing the ratio of urea/NH 4 F or TPAOH/NH 4 F. Then, the sheet HZSM-5 and ZnZr 7 O were connected in tandem to investigate the reaction conditions and catalytic performance for the direct conversion of CO 2 hydrogenation to aromatics. It was found that the HZ-1.5NH 4 F had a large specific surface area, suitable B acid content and more defect sites. These advantages resulted in a high aromatic selectivity of 77.5% and CO 2 conversion of 17.6% over ZnZr 7 O/HZ-1.5NH 4 F. Meanwhile, it exhibits stable performance and no significant deactivation after 80 h of operation. [ABSTRACT FROM AUTHOR]

• The H-ZSM-5 with different morphologies were rationally designed and the synthesis mechanism was illustrated. • Physical mixture of H-ZSM-5 and In 2 O 3 , Cu-Zn-Al and ZnZrO were used to CO 2 hydrogenation to aromatics. • The fewer intermediates were observed on the Cu/ZnO/Al 2 O 3 -sheetZ5 and In 2 O 3 -sheetZ5 in In-situ DRIFTS spectra. • The ZnZr 7 O(5 0 0)-sheet-Z5 showed the best catalytic performance of BTX, the high selectivity of p-xylene was achieved over the ZnZr 7 O(5 0 0)-chainZ5. • Enhanced CO 2 conversion by ZnZr 7 O(5 0 0)-sheet-Z5 catalysts at suitable calcination temperature and oxygen vacancy concentration. The efficient that to concert CO 2 into high value-added chemicals is a promising and potential strategy to reduce the consumption of petroleum resources, especially as an alternative route to MTA, where direct conversion of aromatics can be achieved through CO 2 hydrogenation. Herein, a series of metal oxides (In 2 O 3 , Cu-Zn-Al and ZnZr x O with different Zr/Zn and calcined at different temperatures) and different morphologies of spherical, hollow, sheet, and chain HZSM-5 were rationally designed, and then connected with metal oxides and HZSM-5 in tandem to investigate the reaction conditions and catalytic performance for the direct conversion that from CO 2 hydrogenation to aromatics, the reaction mechanism was investigated using In-situ DRIFTS. Furthermore, due to the synergy between the respective excellent properties of HZSM-5 zeolites and metal oxides, the selectivity of aromatic up to 75.7% and conversion of CO 2 was 14.5% over ZnZr 7 O(5 0 0)-sheet HZSM-5 tandem catalyst, while achieving high selectivity of 64.1% for BTX. Moreover, high selectivity of the target product to xylene was achieved over the ZnZr 7 O(5 0 0)-chain HZSM-5 tandem catalyst due to the fact that the molecular kinetic radius of p-xylene was close to the b-axis pore radius of HZSM-5, and an appropriate increase in the b-axis length was beneficial to improve the selectivity of p-xylene, which opened up a broad path for the design of catalysts for CO 2 hydrogenation to aromatics. [ABSTRACT FROM AUTHOR]

The 1% Zn Z8 (SAC)/Z5 catalyst prepared by steam-assisted crystallization method with ZIF-8 as sacrificial template and Zn source shows high BTX selectivity (69.8%) and excellent stability in MTA reaction. [Display omitted] • The Zn modified HZSM-5 zeolite was prepared by using ZIF-8 as sacrificial template and Zn source. • The steam-assisted crystallization method is the key to the preparation of high crystallinity nano-hierarchical pore structure Zn/Z5 catalyst. • The grain size, physical properties and acidity distribution of Zn/Z5 can be adjusted by controlling the addition amount of ZIF-8. • Appropriate acid distribution, smaller particle size, larger specific surface area and abundant mesoporous structure are the keys to obtaining higher BTX selectivity and excellent stability. 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, N 2 adsorption-desorption, ICP-OES, NH 3 -TPD, Py-IR, XPS, H 2 -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 Zn Z8 (SAC)/Z5 catalyst was improved and the hierarchical pore structure was obtained successfully after introduced ZIF-8 by steam-assisted crystallization method. Among them, Zn Z8 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 Zn Z8 (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(NO 3) 2 as Zn source (1% Zn ZN (SAC)/Z5), there are smaller particle size, larger specific surface area and mesopore volume as well as suitable acid distribution in 1% Zn Z8 (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. [ABSTRACT FROM AUTHOR]

[Display omitted] • The right amount of cobalt ions could induce the formation of Fe 1-x S. • 100 mL orange II solution (30 mg/L) was degraded to 99.9% within 15 min. • OH and h+ played an important role in the photo-Fenton-like process. • FeS 2 -Fe 1-x S exhibited excellent stability and high catalytic degradation activity for other dyes. 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 FeS 2 -Fe 1-x S heterostructure catalyst was prepared by solvothermal method through adding cobalt element to change the particle nucleation process and inhibit the transformation process of pyrrhotite (Fe 1-x S) phase to pyrite (FeS 2) phase. Then, a series of experiments were devised to clarify the catalytic activity of FeS 2 -Fe 1-x S 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 FeS 2 -Fe 1-x S, 2 mM H 2 O 2 and pH = 3.0. In addition, the reusability of the FeS 2 -Fe 1-x S 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 FeS 2 -Fe 1-x S and dissolved oxygen, which could smoothly release Fe2+ and Fe3+ for the activation of H 2 O 2 to produce more hydroxyl radicals. Finally, the degradation pathway of orange II was proposed by detecting intermediates produced in FeS 2 -Fe 1-x S/H 2 O 2 photo-Fenton-like system by liquid chromatography-mass spectrometry (LC-MS). In short, FeS 2 -Fe 1-x S is a promising catalyst for removing the organic pollutants from solutions. [ABSTRACT FROM AUTHOR]

• The Orange II degradation efficiency attained to 98.9% within 15 min. • OH played an important role in the Cu 2 O(SO 4)-Fe9/H 2 O 2 Fenton-like process. • The degradation rate constant of Cu 2 O(SO 4)-Fe9 is 9.33 and 4.07 times of Cu 2 O(SO 4) and α-Fe 2 O 3 , respectively. • Orange II degradation is conducted through destruction of conjugated structures and mineralization. Hematite (α-Fe 2 O 3), 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-Fe 2 O 3), we have successfully synthesized a novel and high active heterogeneous Fenton catalyst α-Fe 2 O 3 /Cu 2 O(SO 4) for the degradation of organic pollutants. The results show that the as-obtained Cu 2 O(SO 4)-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 Cu 2 O(SO 4)-Fe9 catalyst, 3 mM H 2 O 2 and pH = 3.5. The degradation rate constants of Cu 2 O(SO 4)-Fe9 in the photo-Fenton-like system are 9.33 and 4.07 times of Cu 2 O(SO 4) and α-Fe 2 O 3 , respectively. In addition, the mechanism and pathway for the degradation of Orange II were proposed. The scheme of combining copper-based oxysulfate Cu 2 O(SO 4) with hematite (α-Fe 2 O 3) could improve the efficiency of charge carrier separation, which will further enhance the catalytic activity and expand its application in water purification. [ABSTRACT FROM AUTHOR]