Real-world Study on the Effect of PARPi as Maintenance Therapy on Platinum Sensitivity after First- and Second-line Chemotherapy in Patients with Recurrent High-grade Serous Epithelial Ovarian Cancer.

BACKGROUND: This study investigated the effect of poly(ADP-ribose) polymerase inhibitors (PARPi) as maintenance therapy after first- and second-line chemotherapy on platinum sensitivity in patients with recurrent high-grade serous epithelial ovarian cancer (rHGSOC). METHODS: This study retrospectively analyzed 172 patients with rHGSOC treated at Zhejiang Cancer Hospital and Jiaxing Maternity and Child Health Care Hospital between January 2017 and December 2021. The 1st-PARPi group comprised patients who received a PARPi as maintenance therapy after first-line chemotherapy (n=23), and the 1st-control group comprised those who did not (n = 105). Similarly, the 2nd-PARPi group comprised patients not given a PARPi in their first-line treatment (n = 30), and the 2nd-control group comprised those who were given a PARPi (n = 89). RESULTS: Among the 23 patients in the 1st-PARPi group and the 105 patients in the 1st-control group, nine and 99 were platinum-sensitive, and 14 and six were platinum-resistant, respectively (hazard ratio [HR]: 14.46, P < 0.0001). Among the 30 patients in the 2nd-PARPi group and 89 patients in the 2nd-control group, 10 and 71 were platinum-sensitive, and 20 and 18 were platinumresistant, respectively (HR: 4.37, P < 0.0001). Age, stage, residual tumor, the courses of platinumbased chemotherapy, and breast cancer susceptibility gene mutations were not associated with platinum sensitivity when using a PARPi as maintenance therapy after first- and second-line chemotherapy. CONCLUSION: Patients with rHGSOC using a PARPi were more likely to be platinum-sensitive and develop platinum resistance independent of PARPi duration. Care should be taken when using a PARPi as maintenance therapy after first- and second-line chemotherapy.

A multicenter noninferior randomized controlled study of sentinel lymph node biopsy alone versus sentinel lymph node biopsy plus lymphadenectomy for patients with stage I endometrial cancer, INSEC trial concept.

BACKGROUND: Up to the present time, there has remained a lack of strong evidence as to whether sentinel lymph node biopsy can replace lymphadenectomy for early endometrial cancer. The traditional surgery for endometrial cancer includes pelvic lymphadenectomy and paraaortic lymph node resection, but complications often seriously affect patients' quality of life. Two randomized controlled trials with large samples have proved that lymphadenectomy does not improve the overall recurrence rate and survival rate of patients. On the contrary, it increases the incidence of complications and even mortality. The current trial is designed to clarify whether sentinel lymph node biopsy can replace lymphadenectomy for early endometrial cancer patients with negative lymph nodes. METHODS: This study is a randomized, open-label, multicenter and non-inferiority controlled clinical trial in China. Potential participants will be patients with pathologically confirmed endometrial cancer at the Zhejiang Cancer Hospital, Jiaxing Maternity and Child Health Care Hospital, and the First Hospital of Jiaxing in China. The total sample size for this study is 722. Patients will be randomly assigned in a 1:1 ratio to two groups. Patients in one group will undergo sentinel lymph node biopsy + total hysterectomy + bilateral salpingo-oophorectomy ± paraaortic lymph node resection. Patients in the other group will undergo sentinel lymph node biopsy + total hysterectomy + bilateral salpingo-oophorectomy + pelvic lymphadenectomy ± paraaortic lymph node resection. The 3-year disease-free survival rate, overall survival rate, quality of life (use EORTC QLQ-C30 + QLQ-CX24), and perioperative related indexes of the two groups will be compared. RESULTS: We expect to find that for patients with early endometrial cancer, the 3-year disease-free survival rate following sentinel lymph node biopsy with indocyanine green combined with near-infrared fluorescence imaging is similar to that following lymphadenectomy. The operation time, as well as incidence of pelvic lymphocyst, lymphedema of lower limb, and edema of vulva in patients who only undergo sentinel lymph node biopsy are expected to be significantly lower than in patients who undergo lymphadenectomy. The quality of life of patients who undergo sentinel lymph node biopsy alone will be significantly better than that of patients who undergo lymph node dissection. CONCLUSION: This will prove that the prognosis of sentinel lymph node biopsy alone with indocyanine green combined with near-infrared fluorescence imaging is not inferior to that of sentinel lymph node biopsy plus lymphadenectomy for early stage endometrial cancer with negative nodal assessment intraoperatively. In addition, sentinel lymph node biopsy alone with indocyanine green combined with near-infrared fluorescence imaging results in fewer surgical complications and gives patients better quality of life. TRIAL REGISTRATION: chictr.org.cn, ChiCTR1900023161. Registered 14 May 2019, http://www.chictr.org.cn/edit.aspx?pid=38659&htm=4 .

Atomic Insights into the Cu Species Supported on Zeolite for Direct Oxidation of Methane to Methanol via Low-Damage HAADF-STEM.

Precise determination of the structure-property relationship of zeolite-based metal catalysts is critical for the development toward practical applications. However, the scarcity of real-space imaging of zeolite-based low-atomic-number (LAN) metal materials due to the electron-beam sensitivity of zeolites has led to continuous debates regarding the exact LAN metal configurations. Here, a low-damage high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging technique is employed for direct visualization and determination of LAN metal (Cu) species in ZSM-5 zeolite frameworks. The structures of the Cu species are revealed based on the microscopy evidence and also proved by the complementary spectroscopy results. The correlation between the characteristic Cu size in Cu/ZSM-5 catalysts and their direct oxidation of methane to methanol reaction properties is unveiled. As a result, the mono-Cu species stably anchored by Al pairs inside the zeolite channels are identified as the key structure for higher C1 oxygenates yield and methanol selectivity for direct oxidation of methane. Meanwhile, the local topological flexibility of the rigid zeolite frameworks induced by the Cu agglomeration in the channels is also revealed. This work exemplifies the combination of microscopy imaging and spectroscopy characterization serves as a complete arsenal for revealing structure-property relationships of the supported metal-zeolite catalysts.

Crystal Engineering of TiO2 for Enhanced Catalytic Oxidation of 1,2-Dichloroethane on a Pt/TiO2 Catalyst.

Crystal engineering of metal oxide supports represents an emerging strategy to improve the catalytic performance of noble metal catalysts in catalytic oxidation of chlorinated volatile organic compounds (CVOCs). Herein, Pt catalysts on a TiO2 support with different crystal phases (rutile, anatase, and mixed phase (P25)) were prepared for catalytic oxidation of 1,2-dichloroethane (DCE). The Pt catalyst on P25-TiO2 (Pt/TiO2-P) showed optimal activity, selectivity, and stability, even under high-space velocity and humidity conditions. Due to the strong interaction between Pt and P25-TiO2 originating from the more lattice defects of TiO2, the Pt/TiO2-P catalyst possessed stable Pt0 and Pt2+ species during DCE oxidation and superior redox property, resulting in high activity and stability. Furthermore, the Pt/TiO2-P catalyst possessed abundant hydroxyl groups, which prompted the removal of chlorine species in the form of HCl and significantly decreased the selectivity of vinyl chloride (VC) as the main byproduct. On the other hand, the Pt/TiO2-P catalyst exhibited a different reaction path, in which the hydroxyl groups on its surface activated DCE to form VC and enolic species, besides the lattice oxygen of TiO2 for the Pt catalysts on rutile and anatase TiO2. This work provides guidance for the rational design of catalysts for CVOCs.

Highly Efficient Oxidation of Propane at Low Temperature over a Pt-Based Catalyst by Optimization Support.

Pt-based catalysts have attracted widespread attention in environmental protection applications, especially in the catalytic destruction of light alkane pollutants. However, developing a satisfying platinum catalyst with high activity, excellent water-resistance, and practical suitability for hydrocarbon combustion at low temperature is challenging. In this study, the Pt catalyst supported on the selected Nb2O5 oxide exhibited an efficient catalytic activity in propane oxidation and exceeded that of most catalysts reported in the literature. More importantly, the Pt/Nb2O5 catalyst maintained excellent activity and durability even after high-temperature aging at 700 °C and under harsh working conditions, such as a certain degree of moisture, high space velocity, and composite pollutants. The excellent performance of the Pt/Nb2O5 catalyst was attributed to the abundant metallic Pt species stabilized on the surface of Nb2O5, which prompted the C-H bond dissociation ability as the rate-determining step. Furthermore, propane was initially activated via oxidehydrogenation and followed the acrylate species path as a more efficient propane oxidation path on the Pt/Nb2O5 surface. Overall, Pt/Nb2O5 can be considered a promising catalyst for the catalytic oxidation of alkanes from industrial sources and could provide inspiration for designing superb catalysts for the oxidation of light alkanes.

Vinyl chloride catalytic combustion on Pt/CeO2: Tuning Pt chemical state to promote Cl removing.

Supported Pt catalysts usually produce chlorinated byproducts during chlorinated volatile organic compounds (CVOCs) combustion, the removal of formed surface chlorine species is the key to improve the activity, selectivity and stability. In this paper, the Pt chemical state is adjusted by the interaction between Pt and CeO2 through controlling the morphology of CeO2, which further affects the catalytic performance of VC combustion. For Pt/CeO2-octahedron, the weak interaction between Pt and CeO2 results in the formation of PtO2, facilities VC adsorption and C-Cl bonds cleavage and becomes a key active site to accommodate the dissociated Cl species. While the strong interaction leads to the formation of PtxCe1-xO2-σ solid solution on Pt/CeO2-rod has relative lower ability in Cl species removal compared with PtO2. Density functional theory (DFT) calculations also confirms that the introduced Pt species reduces the concentration of Cl species on the surface as well as the chlorinated-byproducts. Hence, Pt/CeO2-octahedron outperformed Pt/CeO2-rod and Pt/CeO2-cube with 90% VC conversion at 280 °C. Furthermore, under the same VC conversion (90%), the concentration of chlorinated byproducts on Pt/CeO2-octahedron was only 4% than that of Pt/CeO2-rod.

Total Oxidation of Light Alkane over Phosphate-Modified Pt/CeO2 Catalysts.

Developing efficient catalysts for the total oxidation of light alkane at low temperatures is challenging. In this study, superior catalytic performance in the total oxidation of light alkane was achieved by modulating the acidity and redox property of a Pt/CeO2 catalyst through phosphorus modification. Surface modification with phosphorus resulted in electron withdrawal from Pt, leading to platinum species with high valency and the generation of Brönsted acid sites, leading to increased acidity of the Pt/CeO2 catalyst. Consequently, the ability of the Pt/CeO2 catalyst to activate the C-H bond increased with increasing P content in the catalyst owing to the synergistic effect of Ptδ+-(CeO2-POx)δ- dipolar catalytic sites. In contrast, the redox property of the Pt/CeO2 catalyst weakened at first; subsequently, it was partially restored owing to the recovery of a part of the bare ceria surface with increasing P content. The turnover frequency in propane oxidation over the phosphate-modified Pt/CeO2 catalyst with a P/Ce atomic ratio of 0.06 was 10-fold higher than that over the unmodified Pt/CeO2 catalyst at 220 °C. This comprehensive study not only sheds light on the mechanism underlying the surface modification process but also offers a strategy for realizing higher catalytic activity in the total oxidation of light alkanes.

Oxy-Anionic Doping: A New Strategy for Improving Selectivity of Ru/CeO2 with Synergetic Versatility and Thermal Stability for Catalytic Oxidation of Chlorinated Volatile Organic Compounds.

Understanding the formation and inhibition of more toxic polychlorinated byproducts from the catalytic oxidation elimination of chlorinated volatile organic compounds (Cl-VOCs) and unveiling efficient strategies have been essential and challenging. Here, RuOx supported on CePO4-doped CeO2 nanosheets (Ru/Pi-CeO2) is designed for boosting catalytic oxidation for the removal of dichloromethane (DCM) as a representative Cl-VOC. The promoted acid strength/number and sintering resistance due to the doping of electron-rich and thermally stable CePO4 are observed along with the undescended redox ability and the exposed multi-active sites, which demonstrates a high activity and durability of DCM oxidation (4000 mg/m3 and 15,000 mL/g·h, stable complete-oxidation at 300 °C), exceptional versatility for different Cl-VOCs, alkanes, aromatics, N-containing VOCs, CO and their multicomponent VOCs, and enhanced thermal stability. The suppression of polychlorinated byproducts is determined over Ru/Pi-CeO2 and oxy-anionic S, V, Mo, Nb, or W doping CeO2, thus the oxy-anionic doping strategy is proposed based on the quenching of the electron-rich oxy-anions on chlorine radicals. Moreover, the simple mechanical mixing with these oxy-anionic salts is also workable even for other catalysts such as Co, Sn, Mn, and noble metal-based catalysts. This work offers further insights into the inhibition of polychlorinated byproducts and contributes to the convenient manufacture of monolithic catalysts with superior chlorine-poisoning resistance for the catalytic oxidation of Cl-VOCs.

Spherical Ni Nanoparticles Supported by Nanosheet-Assembled Al2O3 for Dry Reforming of CH4: Elucidating the Induction Period and Its Excellent Resistance to Coking.

The design and preparation of efficient coking-resistant catalysts for dry reforming of methane (DRM) is significant for industrial applications but a challenge for supported Ni catalysts. Nanosheet-assembled Al2O3 (NA-Al2O3) with hierarchical hollow microspheres was used to support Ni nanoparticles, which exhibits superior long-time stability and coking resistance for the DRM reaction from 700 to 800 °C without coke deposition. Active Ni species, exsolved from NiAl2O4 spinel, are aggregated into Ni nanoparticles and finally stabilize as spherical Ni nanoparticles of 18.0 nm due to the spatial confinement of hierarchical hollow microspheres of the NA-Al2O3 support after the DRM reaction for 60 h. The catalytic activity in the induction period of the Ni/(NA-Al2O3) catalyst increases because of the enhancement of the surface Ni0/(Ni0+Ni2+) ratio, that is, the increment of the amount of active Ni sites. The spherical Ni nanoparticles embedded in the NA-Al2O3 support, superior CO2 adsorption ability, and more surface hydroxyl groups on the Ni/(NA-Al2O3) catalyst are the determining factors for its long-time stability and excellent anti-coking for the DRM reaction.

Significant Improvement of Catalytic Performance for Chlorinated Volatile Organic Compound Oxidation over RuOx Supported on Acid-Etched Co3O4.

Ru catalysts have attracted increasing attention in catalytic oxidation of chlorinated volatile organic compounds (CVOCs). However, the development of Ru catalysts with high activity and thermal stability for CVOC oxidation still poses significant challenges due to their restrictive relationship. Herein, a strategy for constructing surface defects on Co3O4 support by acid etching was utilized to strengthen the interaction between active RuOx species and the Co3O4 support. Consequently, both the dispersity and thermal stability of RuOx species were significantly improved, achieving both high activity and stability of Ru catalysts for CVOC oxidation. The optimized Ru catalyst on the HF-etched Co3O4 support (Ru/Co3O4-F) achieved complete oxidation of vinyl chloride at 260 °C under 30 000 mL·g-1·h-1, which was lower than 300 °C for the Ru catalyst on the original Co3O4 (Ru/Co3O4). More importantly, the Ru species on the Ru/Co3O4-F catalyst were hardly lost after calcination at 500-700 °C and even reacting at 650 °C for 120 h. On this basis, the polychlorinated byproducts over the Ru/Co3O4-F catalyst were almost completely effaced by phosphate modification on the catalyst surface. These findings show that the method combining acid etching of the support and phosphate modification provides a strategy for the advancement of catalyst design for CVOC oxidation.

Heat maps present the spatial distribution of human papillomavirus infection in Zhejiang Province, China.

Determining the spatial distribution of human papillomavirus (HPV) and performing accurate public health analyses helps to distinguish areas of healthcare that require further research, and enables therapeutic techniques and approaches in healthcare to be focused more accurately. A total of 4,560 women were enrolled in the present study. Flow-through hybridization and gene chip assays were used to detect the genotypes of HPV infection. Heat maps were then generated to present the spatial distribution of HPV infections in Zhejiang Province according to genotype. Of the exfoliated cervical cell samples from the 4,560 women, HPV was detected in 1,886 samples. HPV-16, -58, -52 and -18 were the most prevalently identified genotypes in the population included in the present study. HPV-16 and -58 infections were mainly distributed in the northern and central regions of Zhejiang Province, such as in Hangzhou and Shaoxing, where the prevalence was higher than that in the southern regions (P<0.05). HPV-18 infection was widespread throughout Zhejiang Province, but had a much lower infection rate in Ningbo and Huzhou (P<0.05). High infection rates of HPV-52 were mainly detected in Hangzhou and the eastern coastal areas of Wenzhou, with a relatively low rate of infection in the center of the province (P<0.05). In conclusion, HPV-16, -58, -52 and -18 were the four most prevalent HPV genotypes observed in Zhejiang Province. Heat maps were created to display the spatial distribution of HPV infection according to genotype, which varied by geographical regions. The results indicate that for individuals in Ningbo or Wenzhou, bivalent or quadrivalent vaccines may be suitable, but for those in Hangzhou and Shaoxing, nonavalent vaccines are strongly recommended.

Catalytic mechanism and pathways of 1, 2-dichloropropane oxidation over LaMnO3 perovskite: An experimental and DFT study.

The rational comprehension on the catalytic mechanism and pathways of chlorinated volatile organic compounds (CVOCs) oxidation is meaningful for the design of high performance catalytic materials. Herein, we attempted to elucidate the catalytic mechanism and pathways of 1, 2-dichloropropane (1, 2-DCP) oxidation over LaMnO3 perovskite from experimental and theoretical studies. Experimental results indicate that the initial dechlorination of 1, 2-DCP into allyl chloride (AC) can be readily achieved over LaMnO3, while the further decomposition of AC is more vulnerable to be affected by the reaction conditions and strongly dependent on the surface active oxygen species. Density functional theory (DFT) calculation reveals that the heterogeneous conversion of 1, 2-DCP initiates with the chemisorption on the Mn site, followed by the formation of AC via a synergistic mechanism. AC decomposition is considered as the rate-determining step under an inert condition, while the dechlorination of adsorbed 1, 2-DCP dominates the whole reaction under an oxygen atmosphere.

Incorporating Lanthanum into Mesoporous Silica Foam Enhances Enzyme Immobilization and the Activity of Penicillin G Acylase Due to Lewis Acid-Base Interactions.

Penicillin G acylase (PGA) has been immobilized on a lanthanum-incorporated mesostructured cellular foam (La-MCF) support by using the interaction between the strong Lewis acid sites on the surface of La-MCF and the free amino groups of lysine residues of PGA. The La-MCF support was successfully synthesized in situ through the addition of a citric acid (CA) complexant. The results of pyridine-IR spectroscopy show the presence of strong Lewis acid sites on the surface of the prepared La-MCF (with CA), attributed to the incorporation of lanthanum species into the framework of MCF. Through interaction with the strong Lewis acid sites, the enzymes can be firmly immobilized on the surface of the support. The results indicate that PGA/La-MCF (with CA) exhibits a high specific activity and greatly enhanced operational stability. For the hydrolysis of penicillin G potassium salt, the initial specific activity of PGA/La-MCF (with CA) reaches 10023 U/g. Even after being recycled 10 times, PGA/La-MCF (with CA) retains 89 % of its initial specific activity, much higher than the 77 % of PGA/Si-MCF.

Titania-Samarium-Manganese Composite Oxide for the Low-Temperature Selective Catalytic Reduction of NO with NH3.

A novel Ti-doped Sm-Mn mixed oxide (TiSmMnOx) was first designed for the selective catalytic reduction (SCR) of NOx with NH3 at a low temperature. The TiSmMnOx catalyst exhibited a superior catalytic performance, in which NOx conversion higher than 80% and N2 selectivity above 90% could be achieved in a wide-operating temperature window (60-225 °C). Specially, the catalyst also showed high durability against the large space velocity and excellent SO2/H2O resistance. Ti incorporation can efficiently inhibit MnOx crystallization and tune the MnOx phase during calcination at a high temperature. Subsequently, a high specific surface area as well as an increased amount of acid sites on the TiSmMnOx catalysts were produced. Further, the reducibility of the Sm-doped MnOx catalyst was modulated, facilitating NO oxidation and inhibiting NH3 nonselective oxidation. Consequently, a superior SCR activity was achieved at a low temperature and the operating temperature window of the TiSmMnOx catalyst was significantly widened. These findings may provide new insights into the reasonable design and development of the new non-vanadium catalysts with a high NH3-SCR activity for industrial application.

Ambient Temperature NO Adsorber Derived from Pyrolysis of Co-MOF(ZIF-67).

Co-, Ni-, and Zn-containing MOFs are prepared and then pyrolyzed to generate materials for ambient temperature NO adsorption. Materials containing Co are much more efficient for NO adsorption than those containing Ni and Zn; therefore, Co is identified as the active phase. The best performing material studied here achieves 100% low concentration (10 ppm) NO adsorption for more than 15 h under a weight hourly space velocity of 120 000 mL g-1 h-1. Powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopies, along with scanning electron microscopy and TEM, are used to probe the physicochemical properties of the materials, particularly the Co active phase, and chemistries involved in NO adsorption-desorption. NO adsorbs on oxygen-covered Co nanoparticle surfaces in the form of nitrates and desorbs as NO at higher temperatures as a result of surface nitrate decomposition. NO storage capacity decreases gradually upon repeated NO adsorption-desorption cycles, likely because of Co3O4 formation during these processes.

Taming the stability of Pd active phases through a compartmentalizing strategy toward nanostructured catalyst supports.

The design and synthesis of robust sintering-resistant nanocatalysts for high-temperature oxidation reactions is ubiquitous in many industrial catalytic processes and still a big challenge in implementing nanostructured metal catalyst systems. Herein, we demonstrate a strategy for designing robust nanocatalysts through a sintering-resistant support via compartmentalization. Ultrafine palladium active phases can be highly dispersed and thermally stabilized by nanosheet-assembled γ-Al2O3 (NA-Al2O3) architectures. The NA-Al2O3 architectures with unique flowerlike morphologies not only efficiently suppress the lamellar aggregation and irreversible phase transformation of γ-Al2O3 nanosheets at elevated temperatures to avoid the sintering and encapsulation of metal phases, but also exhibit significant structural advantages for heterogeneous reactions, such as fast mass transport and easy access to active sites. This is a facile stabilization strategy that can be further extended to improve the thermal stability of other Al2O3-supported nanocatalysts for industrial catalytic applications, in particular for those involving high-temperature reactions.

Ru/CeO2 Catalyst with Optimized CeO2 Support Morphology and Surface Facets for Propane Combustion.

Tailoring the interfaces between active metal centers and supporting materials is an efficient strategy to obtain a superior catalyst for a certain reaction. Herein, an active interface between Ru and CeO2 was identified and constructed by adjusting the morphology of CeO2 support, such as rods (R), cubes (C), and octahedra (O), to optimize both the activity and the stability of Ru/CeO2 catalyst for propane combustion. We found that the morphology of CeO2 support does not significantly affect the chemical states of Ru species but controls the interaction between the Ru and CeO2, leading to the tuning of oxygen vacancy in the CeO2 surface around the Ru-CeO2 interface. The Ru/CeO2 catalyst possesses more oxygen vacancy when CeO2-R with predominantly exposed CeO2{110} surface facets is used, providing a higher ability to adsorb and activate oxygen and propane. As a result, the Ru/CeO2-R catalyst exhibits higher catalytic activity and stability for propane combustion compared with the Ru/CeO2-C and Ru/CeO2-O catalysts. This work highlights a new strategy for the design of efficient metal/CeO2 catalysts by engineering morphology and associated surface facet of CeO2 support for the elimination of light alkane pollutants and other volatile organic compounds.

Total Oxidation of Propane over a Ru/CeO2 Catalyst at Low Temperature.

Ruthenium (Ru) nanoparticles (∼3 nm) with mass loading ranging from 1.5 to 3.2 wt % are supported on a reducible substrate, cerium dioxide (CeO2, the resultant sample is called Ru/CeO2), for application in the catalytic combustion of propane. Because of the unique electronic configuration of CeO2, a strong metal-support interaction is generated between the Ru nanoparticles and CeO2 to stabilize Ru nanoparticles for oxidation reactions well. In addition, the CeO2 host with high oxygen storage capacity can provide an abundance of active oxygen for redox reactions and thus greatly increases the rates of oxidation reactions or even modifies the redox steps. As a result of such advantages, a remarkably high performance in the total oxidation of propane at low temperature is achieved on Ru/CeO2. This work exemplifies a promising strategy for developing robust supported catalysts for short-chain volatile organic compound removal.

Ruthenium oxides supported on heterostructured CoPO-MCF materials for catalytic oxidation of vinyl chloride emissions.

A novel heterostructured material, cobalt phosphate-SiO2 mesostructured cellular foams (CoPO-MCF), was successfully synthesized by in situ growth. The material was characterized by X-ray diffraction (XRD), nitrogen sorption, temperature-programmed reduction (H2-TPR and CO-TPR), temperature-programmed desorption of NH3 (NH3-TPD), and X-ray photoelectron spectroscopy (XPS). A ruthenium precursor was readily introduced and highly dispersed on the CoPO nanophases of the CoPO-MCF through an impregnation method. The resulting Ru/CoPO-MCF catalyst exhibited high catalytic activity for the oxidation of vinyl chloride (VC). The results of three consecutive runs and long-term tests showed high stability of the Ru/CoPO-MCF for the catalytic oxidation of VC. The unique heterostructures of the CoPO-MCF not only improve the reducibility and acidity of the MCF but also strengthen the interaction between ruthenium oxide nanoparticles and the CoPO-MCF support, which contributes to the enhanced catalytic performance.

Significant enhancement of the selectivity of propylene epoxidation for propylene oxide: a molecular oxygen mechanism.

As an attractive and environmentally friendly process for propylene oxide (PO) production, direct epoxidation of propylene (DEP) with molecular oxygen catalyzed by metal-based catalysts such as Ag and Cu has drawn much attention, but remains one of the biggest challenges in chemistry. In this work, the crucial competitive reactions of propylene α-H stripping (AHS) versus the oxametallacycle formation (OMMP formation) using adsorbed atomic oxygen (O*) or adsorbed molecular oxygen (O2*) as an oxidant are extensively compared on IB group metal surfaces (Cu, Ag and Au) with varied electronic and structural effects in order to explore the possibility to enhance the PO selectivity by virtue of first-principles calculations. The determining factor for the PO selectivity is quantitatively revealed: it is found that with atomic O*, the AHS pathway was preferred, indicating the reason for low PO selectivity with current catalysts. By contrast, the undissociated molecular O2* species is found to prefer to electrophilically attack the C[double bond, length as m-dash]C double bond of propylene and form a special oxametallacycle intermediate (OOMMP) rather than nucleophilically abstracting the α-H. This OOMMP can readily cleave the O-O bond and transform into OMMP. These results demonstrate that the presence of undissociated O2* can efficiently promote the PO selectivity. Furthermore, the merit of such a molecular O2* mechanism can be rationalized by our quantitative barrier decomposition analyses, which reveal that the lower hydrogen affinity (ΔEH) of the O2* species dominantly contributes to the limited AHS reaction, and boosts the OMMP selectivity. Therefore, ΔEH can be applied as a selectivity descriptor. An efficient strategy to promote PO formation is presented. The insight obtained could pave the way for further development of catalysts for propylene epoxidation.