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Based on the molecular understanding of coking and decoking chemistry in zeolite-catalyzed MTO process, we proposed a steam regeneration strategy mingling resource utilization of PAHs and avoiding CO2emission from coke combustion in air.

Mesoporous high-silica zeolite Y with advantages of improved accessibility of acid sites and mass transport properties is highly desired catalytic materials for oil refinery, fine chemistry and emerging biorefinery. Here, we report the direct synthesis of mesoporous high-silica zeolite Y (named MSY, SiO2/Al2O3≥ 9.8) and their excellent catalytic cracking performance. The obtained MSY materials are mesoporous single crystals with octahedral morphology, abundant mesoporosity and excellent (hydro)thermal stability. Both the acid concentration and acid strength of H-form MSY are obviously higher than those of commercial ultra-stable Y (USY), which should be attributed to the uniform Al distribution of MSY zeolite. The H-MSY displays an obviously reduced deactivation rate and improved catalytic activity in the cracking reaction of bulky 1,3,5-triisopropylbenzene (TIPB), as compared with its mesoporogen-free counterpart and USY. In addition, H-MSY was investigated as catalyst for the cracking of industrial heavy oil. The MSY-based catalyst (after aging at 800 oC in 100% steam for 17 h) exhibits superior conversion (7.64% increase) and gasoline yield (16.37% increase) than industrial fluid catalytic cracking (FCC) catalyst under the investigated conditions.

In this issue of Chem Catalysis, Wang et al. report high-performance CoMnAl/HZSM-5 bifunctional catalysts for application in the transformation of syngas to aromatics. The versatile HZSM-5@silicalite-1 zeolites, with a hollow nanostructure and a scaly shell, were fabricated to regulate the selective synthesis of aromatic products, especially para-xylene.

The SAPO-34 catalyst was fine-tuned with zinc cations through a straightforward template-assisted ion incorporation (TII) process, without the necessary template pre-removal and the preparation of NH4-SAPO-34 intermediate, which is more facile, efficient and cost-effective than the conventional ion exchange process. The template-assisted zinc cations incorporated SAPO-34 catalysts were characterized by XRD, XRF, N2adsorption-desorption, XPS, SEM, EDX, 1H NMR, respectively. Enhanced selectivity to ethylene and ratio of ethylene to propylene in MTO reaction are observed over the zinc cations modified SAPO-34 catalysts, due to the facilitated formation of lower methylbenzenes that favour the ethylene generation, as well as the increased diffusion hindrance originated from the zinc cations incorporation and the facilitated generation of aromatics compound.

The AEI cavity of SAPO-18 catalyst was modified with zinc cations with the conventional ion exchange procedure. The cavity modification effectively tunes the product selectivity, and shifts the products from mainly propylene to comparable production of ethylene and propylene in methanol to olefin (MTO) reaction. The incorporation of zinc ions and the generation of bicyclic aromatic species in the AEI cavity of SAPO-18 catalysts introduce additional diffusion hindrance that exert greater influence on the relatively bulky products (e.g. propylene and higher olefins), which increase the selectivity to small-sized products (e.g. ethylene). It appears that the incorporated zinc cations facilitate the generation of lower methylbenzenes which promote the generation of ethylene. The cavity modification via incorporating zinc ions effectively tunes the product selectivity over SAPO molecular sieves with relatively larger cavity, which provides a novel strategy to develop the potential alternative to SAPO-34 catalysts for industrial MTO reaction.

Achieving multiple high-value-added chemical production through novel reaction processes and shape-selective catalytic strategy is the key to realizing efficient low-carbon catalytic processes. In this work, a methanol–toluene coreaction system was developed, and combined control strategies of reaction pathway guidance and shape-selective catalysis were applied for the successful production of light olefins and para-xylene on single HZSM-5 catalyst bed. Cofeeding toluene additionally provides reactive and flowing aromatic hydrocarbon pool species that change the dominant reaction pathway in the complex network of the methanol reaction on HZSM-5 and promote the formation of ethylene. For the first time, the key reaction intermediates methylmethylenecyclodiene are directly captured and identified by experimental and theoretical techniques. This helps to propose the catalytic cycle for the dominant generation of ethylene and, more importantly, enriches the methanol-to-hydrocarbons (MTH) chemistry and hydrocarbon pool mechanism. Furthermore, 0.4HZSM-5@S-1-CLD, an optimized HZSM-5 catalyst modified by the silicalite-1 epitaxial growth followed by silanization approach, realizes highly selective production of light olefins (especially ethylene) and para-xylene, while excellent reactant activity is maintained. This highly efficient coreaction route gives an important leading significance in synthesizing the raw materials for the polyolefin and polyester industries. The establishment of the combined control strategies provides a model for the joint production of multiple target chemicals in complex catalytic processes.

In situ FTIR and XANES analyses elucidate the dynamic gallium hydride species under working conditions, serving as the active sites for propane-CO2coupling conversion to aromatics and syngas.

PurposeThree-dimensional (3D) scans with flat detector angiographic systems are widely used for neurointerventions by providing detailed vascular information. However, its associated radiation dose and streak metal artifact generated by implanted treatment devices remain issues. This work evaluates the feasibility and clinical value of volume of interest imaging combined with metal artifact reduction (VOI+MAR) to generate high quality 3D images with reduced radiation dose and metal artifacts.Material and methodsFull volume (FV) and VOI scans were acquired in 25 patients with intracranial aneurysms and treated with either endovascular coiling (n=9) or stent assisted coiling (n=16) procedures. FV and VOI scans were reconstructed with conventional syngoDynaCT and VOI +MAR prototype software, respectively.ResultsQuantitative evaluation results demonstrated that compared with standard FV syngoDynaCT images, overall image quality was improved in the VOI+MAR reconstructed images, with streak metal artifacts considerably reduced or even removed; details of soft tissue in the vicinity of the metal devices was well preserved or recovered in the majority of cases. Radiation dose to patients calculated by dose area product was found to be significantly reduced using VOI scans.ConclusionThis study confirmed the feasibility of using VOI+MAR prototype software to achieve high image quality of a small volume of clinical interest and to reduce radiation dose. This technique has potential to improve patient safety and treatment outcomes.

The SAPO-34 catalysts were modified with metal cations by different processes (conventional ion exchange (CIE), template-assisted ion incorporation (TII) and alcoholic ion exchange (AIE)), systematically characterized by XRD, XRF, N2adsorption-desorption, UV-VIS, H2-TPR, EPR, SEM, EDX, XPS, NH3-TPD, 1H NMR and IGA, and applied in MTO reaction. The metal cations incorporation introduces extra diffusion hindrance by metallic species located in the cavity of SAPO-34. In particular, the Zn cations-modified SAPO-34 catalysts exhibit core-shell like structure, with Si-rich and Zn-rich sublayer near the external surface, which favors the coke deposition at the beginning of MTO reaction, exerts marked impact on the diffusion of the generated products with relatively large molecular size (e.g. propylene), and significantly increases the selectivity to ethylene and the ratio of ethylene to propene in the MTO reaction.

Photoelectrochemical water splitting provides an attractive way to store solar energy in molecular hydrogen as a kind of sustainable fuel. To achieve high solar conversion efficiency, the most stringent criteria are effective charge separation and injection in electrodes. Herein, efficient photoelectrochemical water oxidation is realized by optimizing charge separation and surface charge transfer of GaN:ZnO photoanode. The charge separation can be greatly improved through modified moisture-assisted nitridation and HCl acid treatment, by which the interfaces in GaN:ZnO solid solution particles are optimized and recombination centers existing at the interfaces are depressed in GaN:ZnO photoanode. Moreover, a multimetal phosphide of NiCoFeP was employed as water oxidation cocatalyst to improve the charge injection at the photoanode/electrolyte interface. Consequently, it significantly decreases the overpotential and brings the photocurrent to a benchmark of 3.9 mA cm–2at 1.23 V vs RHE and a solar conversion efficiency over 1% was obtained.

Carbon dioxide (CO2) and methane (CH4) are major greenhouse gases, and the use of these C1 resources to produce high-value chemicals is significant for sustainable chemistry. Due to the high stability and C–C coupling barriers, simultaneous conversion of CO2and CH4to aromatics remains challenging. Herein, we report a sustainable strategy for utilizing greenhouse gases based on the conversion of CO2and CH3Cl, an alternative of CH4, that yields a high aromatics selectivity (71.3%) with ∼50% BTX selectivity using H–ZSM–5 as catalyst at 723 K and 3 MPa. In situcharacterization and 13C isotope-labeling experiments demonstrate that CO2directly participates in the formation of aromatics via lactone species instead of undergoing a classical reverse water-gas shift reaction. Furthermore, a unique mechanism for CO2conversion is proposed, involving the formation and subsequent transformation of lactone and cyclopentenone species. This work expands high carbon utilization pathways for converting greenhouse gases into chemicals.

AimTo evaluate the accuracy of three-dimensional (3D) images from two modalities—CT angiography (CTA) and digital subtraction angiography (DSA). Additionally, to explore the value of using preprocedural CTA for real-time guidance during neurointerventional procedures.Materials and methods25 patients with CTA-confirmed cerebral arterial lesions were enrolled. For 12 of these patients, 3D DSA images of the contrast medium-enhanced target vessel were acquired during the intervention and registered with the preprocedurally acquired CTA images for evaluation of the accuracy of image fusion, focusing on the target vessel and the lesion. For the other 13 patients, a low-dose non-contrast 3D angiographic scan was performed. The preprocedurally acquired CTA image was then registered with the coordinate of angiography and overlaid onto the live fluoroscopic image to provide interventional guidance.ResultsBased on visual inspection by two experienced physicians and quantitative evaluation, excellent accuracy in the 3D registration of the CTA and DSA was achieved for all 12 patients examined. Additionally, CTA could be used successfully to guide the interventional procedures, including both diagnostic DSA and stent treatment. The radiation dose and contrast medium use were compared with those used by conventional interventional procedures and both were found to be significantly reduced.Conclusions3D CTA and angiographic image fusion was approved as highly accurate for neurovasculature. Additionally, using the fusion technique to guide interventional procedures enhanced the workflow, and required much less radiation exposure and contrast medium use, thus helping to reduce potential risks and increase treatment safety.

The recent advances in synthesis and catalytic applications of nano-hierarchical SAPO-34 for methanol-to-olefin (MTO) conversion and other reactions have been elaborated in this minireview. The structure, unique properties (e.g., shape selectivity), and diffusion of zeolites and molecular sieves are briefly covered in the first part. An overview of the development of synthetic methods for the preparation of nanosized SAPO-34 and hierarchical SAPO-34 is included in the second and third parts, with focus on the novel and green preparation strategies. The advantages and disadvantages of the different synthetic approaches are discussed in detail, and the relationship between the catalytic performance and the diffusion and acidity is also elucidated. Finally, the updated characterization techniques considering the interconnectivity between the pore channels are outlined.

Developing highly efficient methods to selectively incorporate active metal sites into the zeolite framework is crucial for the large-scale utilization of metal-zeolites in various catalytic reactions including alkane conversion. Herein, ferrous gluconate is developed as an efficient metal precursor to embed Fe atoms into the MFI siliceous zeolite framework. The crystallization time and Si/Fe ratio are systematically investigated. It is revealed that the ferrous gluconate is well soluble and stable under alkaline conditions, allowing ferrous gluconate to participate in the whole crystallization course of zeolite. Multiple characterizations demonstrate that the tetrahedrally coordinated Fe atoms are selectively incorporated into the MFI siliceous zeolite framework (Fe-MFI). A catalytic test in propane dehydrogenation shows that the optimized Fe-MFI zeolite possesses high activity, propylene selectivity, and durability. This study opens an efficient strategy to incorporate isolated Fe atoms into the zeolite framework.

Phase-junctions formed in mixed crystalline phases of semiconductor based photocatalysts (TiO2and Ga2O3) shows enhanced photocatalytic activity owing to efficient separation of photogenerated charges. However, the phase junction effect on charge separation has not been directly verified yet. In this study, we fabricated a prototype photovoltaic device based on TiO2rutile/anatase coaxial nanorod arrays (NRAs) to demonstrate charge separation at the interface of polymorphic crystal phases. The device—FTO/rutile NRAs/anatase/ITO shows an ordinary photovoltaic response (open-circuit voltage Voc: 154mV, short-circuit current density Jsc: 1.76mA/cm2), contrasting with photo resistor behavior of two TiO2single phase devices of core–core (FTO/rutile NRAs/ITO) and shell–shell (FTO/anatase/ITO). Experimental evidences suggest that the built-in electric field at the interface of rutile/anatase phase junctions in the FTO/rutile NRAs/anatase/ITO device provides the direct driving force for efficient separation of photogenerated charges. The demonstrated strategy of fabricating phase-junction photovoltaic devices may inspire further investigations on new device converting solar into electrical energy and highlight the key role of the phase junction interface in the properties of the mix-phase photocatalysts.

Overall water splitting on a TiO2-based photocatalyst has been extensively investigated. However, in most cases, the products are not in a stoichiometric ratio, thus the reaction is not really overall water splitting. In this work, we found that in the presence of Cl−, the evolution of O2and H2over Pt/TiO2can be successfully achieved, and the activity can be enhanced up to 3 times compared to having no Cl−present. Furthermore, the H2 : O2ratio can be close to 2.0, i.e.the stoichiometric ratio of overall water splitting. It is proposed that the Cl−ion is involved with the reaction intermediate of O2evolution from water oxidation. Our work not only reported overall water splitting on a TiO2-based photocatalyst, but also provided experimental evidence for understanding the possible reaction process and the mechanism of photocatalytic water splitting.

This study investigated the feasibility of using intra-arterial injection-based cerebral blood volume (CBV) imaging with flat detector computed tomography (CT, IAFD-CBV). It is proven that this new method could provide comparable physiologic information as standard intravenous injection-based multi-slice computed tomography CBV imaging (IVCT-CBV).Twelve patients were examined using both IAFD-CBV and IVCT-CBV. An experienced neuroradiologist read both sets of generated CBV maps. If a physiologic perfusion disorder was detected in standard IVCT-CBV, the focus was to check whether IAFD-CBV indicated the same disorder or not. Otherwise, if no disorder was detected, relative CBV (rCBV) values at different basal ganglia regions were measured for both CBV maps and then compared.For three patients with lesions, IAFD-CBV and IVCT-CBV showed similar perfusion disorders in the corresponding regions. For nine patients without lesions, both CBV maps showed good symmetry of contrast agent (CA) distribution for left/right hemisphere, the total average of rCBV was found to be 0.94 –/+0.18 and 1.01 –/+0.14 (1.0 for perfect symmetry) in IAFD-CBV and IVCT-CBV, respectively. However, compared to IVCT-CBV, IAFD-CBV imaging required 70% less contrast agent (CA).In general, a good correlation between IAFD-CBV and IVCT-CBV was found for all 12 patients. Minor deviations of IAFD-CBV were only detected at regions supplied by the middle cerebral artery. IAFD-CBV imaging, which can be directly performed in a catheterization laboratory, was proven to be technically feasible for real-time CBV assessment of the whole brain with good accuracy, and minimized CA usage.

The photocatalytic activity and stability of nanocrystals (NCs) are two important issues for their application in photocatalysis. In this work, we report a combined method to promote the photocatalytic activity as well as the stability of CdS NCs for photocatalytic H2evolution. ZnS shell was grown on CdS NCs forming type I core/shell CdS/ZnS nanocrystals (NCs) to restrain the photocorrosion and passivate the trap states on CdS NCs. Thereafter, dual cocatalysts were loaded to promote the separation and transfer of electrons and holes from the core to outer surface for photocatalytic reactions. It is found that Pt and Ni are effective reduction cocatalysts (RCs) while PdS and PbS are effective oxidation cocatalysts (OCs) for promoting the charge separation and transfer. This strategy was also proved to be effective for other type I core/shell NCs, such as CdTe/CdS/ZnS NCs.

The purpose of this study was to investigate the anatomical accuracy of hardware-based single-photon emission computed tomographycomputed tomography (SPECTCT) registration in the upper abdomen and neck.

The oxygen evolution is kinetically the key step in the photocatalytic water splitting. Cocatalysts could lower the activation potential for O2evolution. However, the cocatalyst for O2evolution has been less investigated, and few effective cocatalysts were reported. This paper reports that the O2evolution rate of photocatalytic water splitting under visible light irradiation can be significantly enhanced when the electrocatalyst cobalt–phosphate (denoted as CoPi) was deposited on BiVO4. The photocurrent density is also greatly enhanced by loading CoPi on BiVO4electrode, and this enhancement in performance shows the similar trend between the photocatalytic activity and photocurrent density. We also found that this tendency is true for BiVO4loaded with a series of different electrocatalysts as the cocatalysts. These results demonstrate that an effective electrocatalyst of water oxidation can be also an effective cocatalyst for O2evolution from photocatalytic water oxidation. By depositing the CoPi as the oxidation cocatalyst and Pt as the reduction cocatalyst on an yttrium-doped BiVO4(Bi0.5Y0.5VO4), overall water splitting reaction to H2and O2was realized. Our work also reveals the essential relations between photocatalysis and electrocatalysis in water splitting reaction.

WS2/CdS photocatalysts with different amounts of WS2cocatalyst are prepared by loading WS2on CdS with an impregnation–sulfidation approach. The transformation process of the tungsten species loaded on CdS together with the junctions formed between WS2and CdS are clearly demonstrated with X-ray photoelectron spectroscopy and transmission electron microscopy. Photocatalytic H2production on WS2/CdS catalysts under visible light (λ > 420 nm) shows that WS2cocatalyst plays a crucial role in H2production. Under optimum conditions, the rate of H2evolution can be increased by up to 28 times when CdS was loaded with only 1.0 wt % WS2, and WS2demonstrates a catalytic performance comparable or even superior to those of noble metals. Photocatalytic reaction results and electrochemical measurements indicate that the significantly enhanced H2evolution of WS2/CdS catalyst mainly owns to the junctions formed between WS2and CdS and the excellent performance of WS2as a cocatalyst in catalyzing H2evolution.

Embedding metal species into zeolite frameworks can create framework-bond metal sites in a confined microenvironment. The metals sitting in the specific T sites of zeolites and their crystalline surroundings are both committed to the interaction with the reactant, participation in the activation, and transient state achievement during the whole catalytic process. Herein, we construct isolated Co-motifs into purely siliceous MFI zeolite frameworks (Co-MFI) and reveal the location and microenvironment of the isolated Co active center in the MFI zeolite framework particularly beneficial for propane dehydrogenation (PDH). The isolated Co-motif with the distorted tetrahedral structure ({(≡SiO)2Co(HO–Si≡)2}, two Co–O–Si bonds, and two pseudobridging hydroxyls (Co···OH–Si) is located at T1(7)and T3(9)sites of the MFI zeolite. DFT calculations and deuterium-labeling reactions verify that the isolated Co-motif together with the MFI microenvironment collectively promotes the PDH reaction by providing an exclusive microenvironment to preactivate C3H8, polarizing the oxygen in Co–O–Si bonds to accept H* ({(≡SiO)CoHδ−(Hδ+O–Si≡)3}), and a scaffold structure to stabilize the C3H7* intermediate. The Co-motif active center in Co-MFI goes through the dynamic evolutions and restoration in electronic states and coordination states in a continuous and repetitive way, which meets the requirements from the series of elementary steps in the PDH catalytic cycle and fulfills the successful catalysis like enzyme catalysis.

Oxygen vacancies are a double-edged sword for photoelectrochemical (PEC) devices and a comprehensive understanding on their role in PEC processes is important. Although there is existing work that illustrates their effect on PEC processes, clarifying the influence of surface and bulk oxygen vacancies, respectively, on the PEC performance is challenging. Herein, we present the fabrication of WO3photoanodes with tunable bulk and surface oxygen vacancy with a novel two-step flame heating approach that is proving to be a powerful platform for this purpose. We found that both the conductivity and trapping state density of the WO3photoanode increase with bulk oxygen vacancy density, leading to a volcano-like relationship between the kinetics of charge separation/transport and bulk oxygen vacancy density. Moreover, both the interfacial charge transfer rate constant and the charge recombination rate constant on the surface of the WO3photoanode increase with surface oxygen vacancy density, which also leads to a volcano-like relationship between the charge injection efficiency and surface oxygen vacancy density. By tuning the surface and bulk oxygen vacancy density simultaneously, the PEC performance of the WO3photoanode was increased by ca. 10 times, which illustrates the strength of delicate oxygen vacancy engineering in optimizing PEC devices.