查找使用阿拉丁产品的科研文献

Achieving controlled vanillin HDO by modulation of oxygen vacancies on the Pd/Nb2O5 surface

Xuan Liu,Hao Xu,Hao Li

The conventional Hydrogenation deoxygenation (HDO) process is accompanied by harsh reaction conditions (high temperature, high hydrogen pressure, and long reaction time), leading to problems such as easy catalyst deactivation and poor product selectivity. Therefore, the design of hydrodeoxygenation catalysts that can achieve controllable reaction paths, directional product selectivity and high reaction efficiency under mild conditions has become the key to the problem. Phenolic resin (RF) formed by resorcinol–formaldehyde condensation reaction was introduced as a carbothermal reducing agent to prepare oxygen defect-rich Pd/Nb 2 O 5 -T-RF catalysts. The concentration of oxygen defects on the catalyst surface was changed by adjusting the calcination temperature, which affected the electronic properties and acid properties of the catalyst surface interface and promoted the C-O bond breaking. At 25 ℃ and 80 min, Pd/Nb 2 O 5 -700-RF obtained 100 % Vanillin (VAN) conversion and 98.0 % 2-methoxy-4-methylphenol (MMP) selectivity, and the catalytic performance was significantly better than that of the catalysts without RF treatment as well as other calcination temperatures. Characterization and experimental results showed that the electron-deficient oxygen defect facilitated the adsorption and activation of vanillin and vanillyl alcohol, while promoting the hydrogen spillover on the catalyst surface and improving the HDO catalytic performance. In addition, the method is universal for reducible transition metal oxides and can be further extended to different metal oxide catalysts and applied to other fields.

Lysosome activable polymeric vorinostat encapsulating PD-L1KD for a combination of HDACi and immunotherapy

Fengkun Lu,Lei Hou,Sizhen Wang,Yingjie Yu,Yunchang Zhang,Linhong Sun,Chen Wang,Zhiqiang Ma,Feng Yang

Enhanced catalytic performance of methane combustion over zeolite-supported Pd catalysts with the lanthanum

Yiquan Xie,Ling Zhang,Yiwen Jiang,Shichao Han,Liang Wang,Xiangju Meng,Feng-Shou Xiao

Catalytic combustion of CH 4 to CO 2 and H 2 O was studied over zeolite-supported Pd catalysts, and it was found that zeolite-supported Pd catalysts can present pronounced discrepancy in the catalytic performance of methane oxidation when Na-ZSM-5 was ion-exchanged with various cations of La, Ni, and Mg. Very interestingly, the Pd catalyst supported by NaLa-ZSM-5 exhibited the best result. Over an optimized catalyst, a complete conversion of methane can be achieved at around 320 °C, which is about 60 °C lower than the temperature needed for Pd/Na-ZSM-5. Physicochemical characterizations such as XRD, SEM, HRTEM, XPS, and ICP-OES techniques were used to investigate the factors influencing the catalytic activity and find out the reasons behind the discrepancy in the catalytic performance of methane combustion over these zeolite-supported Pd catalysts. Based on the characterization results, it is proposed that the Pd dispersion and its chemical states are major factors that govern catalytic performance of methane combustion over these catalysts. To the best of our knowledge, the optimal catalyst in this study stands out compared with other reported similar Pd catalysts for the catalytic combustion of methane in terms of activity.

Pd Nanoparticles Loaded on Ceramic Membranes by Atomic Layer Deposition with Enhanced Catalytic Properties

Jia Lu,Qingqing Chen,Sibai Chen,Hong Jiang,Yefei Liu,Rizhi Chen

Atomic layer deposition (ALD) was adopted for the first time to load Pd nanoparticles on Al2O3 ceramic membranes (CMs) for fabricating catalytic membranes (Pd/CMs). The membrane surface was functionalized with the deposition of TiO2 by ALD and subsequent calcination under different atmospheres [CM-TiO2-A, obtained by calcination under an atmosphere of pure argon; CM-TiO2-H, obtained by calcination under a mixed atmosphere of H2 and Ar (H2/Ar = 1:9 in volume)]. The influence of the TiO2 deposition on the microstructure of catalytic membranes and their catalytic performance in p-nitrophenol reduction to p-aminophenol were investigated in detail. The catalytic activity of Pd/CM-TiO2-H improved by 1.9 times compared to Pd/CM, and 100% conversion of p-nitrophenol to p-aminophenol can be achieved. The X-ray photoelectron spectroscopy (XPS), inductively coupled plasma emission spectroscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy results indicate that the ALD of TiO2 and subsequent calcination under a 10% H2 atmosphere can produce more surface oxygen vacancies, providing more active sites for Pd(hfac)2 adsorption and then promoting the loading of Pd nanoparticles. The XPS and H2 temperature-programmed reduction results suggest that calcining TiO2 under the 10% H2 atmosphere is more beneficial for the removal of the hfac ligands and the reduction of Pd(hfac)2, leading to a higher Pd0 ratio. These two aspects contribute to the superior catalytic activity of Pd/CM-TiO2-H.

Hydrogen accelerated regeneration of FeII in Fenton reaction enhanced by Pd/MOF-808(Zr)

Yang Hu,Hai-Liang Yang,San-Jian Ma,Juan-Hong Li,Xin Liu,Yong-Jing Tian,Long Jin,Zi-Xia Lin

The promotion of Fenton process in organic wastewater treatment has been hindered by the disposal of large amounts of iron sludge derived from the excess addition of ferrous salt. The operation of the Fenton reaction could be maintained using trace level Fe II through the effective acceleration reaction of active hydrogen. However, the H 2 which is the precursor of active hydrogen is insoluble in water. Herein, the composite catalyst Pd/MOF-808(Zr) was introduced into the H 2 -Fenton system to enhance the adsorption and activation of this reducing gas. In this novel improved Fenton system called MHACF-MOF-808(Zr), the hydroxyl radical would be unceasingly produced based on the unceasingly recycling of FeII/FeIII at normal temperature and pressure. 15 mg L −1 sulfamethazine could be thoroughly degraded during 2 h reaction process in the initial condition of 60 mL min −1 H 2 , 20 μmol L −1 Fe II , pH 3, 20 mmol L −1  H 2 O 2 and 2 g L −1  Pd/MOF-808(Zr). And so did 10 mg L −1 2,4-Dichlorophenol. The activity and stability of Pd/MOF-808(Zr) could be maintained after at least 6 consecutive reaction cycles. It provides new insight for improving the inherent shortcoming of the Fenton reaction which will generate large amounts of iron sludge.

Ultrafine Pd@PdPt nanowires with a single-atom alloy shell for efficient formate oxidation

Yu-Chuan Jiang,Yu Ding,Fu-Min Li,Shi-Bin Yin,Dong-Sheng Li,Xi-Fei Li,Yu Chen

The intrinsically sluggish kinetics of Pt towards the formate oxidation reaction (FOR) severely impedes its application in direct formate fuel cells (DFFCs). This study reports the synthesis of ultrafine Pd@PdPt nanowires (NWs) with a Pd–Pt single-atom alloy shell via an atomic galvanic displacement reaction. Pd@PdPt0.024 NWs with optimized composition exhibit a remarkable promoted specific activity of 98.2 A m−2 at 0.59 V towards the FOR, which is a 6.5- and 117.7-fold activity enhancement compared to original Pd NWs and commercial Pt catalysts. Density functional theory (DFT) calculations reveal that the electronic interaction between Pd and Pt as well as the modified Pt coordination environment endow the atomically dispersed Pt active site with an altered d-band structure and unique adsorption properties with a broken scaling relationship. The development of Pd@PdPt0.024 NWs will stimulate deeper insight into the FOR mechanism on Pt and hold promise for practical applications in DFFCs.

Constructing Polyphosphazene Microsphere-Supported Pd Nanocatalysts for Efficient Hydrogenation of Quinolines under Mild Conditions

Xiufang Chen,Qingguang Xiao,Yiguo Yang,Bo Dong,Zhengping Zhao

The efficient hydrogenation of N-heterocycles with H2under mild conditions remains a significant challenge. In this work, polyphosphazene (PZs) microspheres, novel organic–inorganic hybrid materials possessing unique –P=N– structural units and a diverse range of side groups, were used to serve as support for the design of a stable and efficient Pd nanocatalyst (Pd/PZs). The PZs microspheres were prepared by self-assembly induced by precipitation polymerization, and Pd nanoparticles were grown and loaded on the support by a chemical reduction process. Several characterization techniques, including XRD, FTIR, SEM, TEM, XPS, BET and TGA, were used to study the structural features of the nanocomposites. The results revealed that Pd nanoparticles were uniformly distributed on the PZs microspheres, with primary sizes ranging from 4 to 9 nm based on the abundance of functional P/N/O groups in PZs. Remarkably high catalytic activity and stability were observed for the hydrogenation of quinoline compounds using the Pd/PZs nanocatalyst under mild conditions. Rates of 98.9% quinoline conversion and 98.5% 1,2,3,4-tetrahydroquinoline selectivity could be achieved at a low H2pressure (1.5 bar) and temperature (40 °C). A possible reaction mechanism for quinoline hydrogenation over Pd/PZs was proposed. This work presents an innovative approach utilizing a Pd-based nanocatalyst for highly efficient multifunctional hydrogenation.

Support-Induced unusual size dependence of Pd catalysts in chemoselective hydrogenation of para-chloronitrobenzene

Xiaohui Zhang,Qingqing Gu,Yanfu Ma,Qiaoqiao Guan,Rui Jin,Hengwei Wang,Bing Yang,Junling Lu

For supported metal catalysts, the underlying support not only disperses and stabilizes metal particles, but also modulates their electronic structures remarkably, and even directly participates in catalytic reactions. Here we report that Pd nanoparticles (NPs) supported on oxygen-functionalized carbon black (Pd/O-C) show an unexpected inverse trend of selectivity on Pd particle size in chemoselective hydrogenation of para -chloronitrobenzene ( p -CNB), compared to those on carbon black (Pd/C). In situ X-ray photoemission spectroscopy reveals that the Pd NPs are more positively charged with decrease of particle size in both samples, while the Pd NPs in Pd/O-C have relatively higher fractions of positive Pd δ+ species than those in Pd/C with similar sizes. Fourier transform infrared spectroscopy shows that the balance of positive Pd δ+ species strongly modulates the competitive adsorption of -NO 2 and -Cl group in p -CNB according to their different electronegativities. As a consequence, we, for the first time, demonstrate that a moderate positive charge of Pd NPs is essential to improve the p- chloroaniline ( p -CAN) selectivity, while too high or too low positive charge could impel the adsorption of the less negatively charged -Cl group, thus generating the dehalogenated aniline by-product. These findings suggest that precise tailoring of the electronic structures of metal NPs could be essential for design of high chemoselective metal catalysts.

Poly (γ-Glutamic Acid) Promotes Enhanced Dechlorination of p-Chlorophenol by Fe-Pd Nanoparticles

Zhang Shiyu,Zhang Chao,Liu Mingyue,Huang Renliang,Su Rongxin,Qi Wei,He Zhimin

Nanoscale zero-valent iron (nZVI) has shown considerable promise in the treatment of chlorinated organic compounds, but rapid aggregation and inactivation hinder its application. In this study, palladium-doped zero-valent iron nanoparticles involving poly (γ-glutamic acid) (Fe-Pd@PGA NPs) were synthesized. The nanoparticles were small (~100 nm), uniformly distributed, and highly stable. The dechlorination performance of Fe-Pd@PGA NPs was evaluated using p -CP as a model. The results demonstrated that Fe-Pd@PGA NPs show high activity even in weakly alkaline conditions. The maximum rate constant reached 0.331 min − 1 at pH 9.0 with a Fe to p -CP ratio of 100. Additionally, the dechlorination activity of Fe-Pd@PGA NPs is more than ten times higher than that of the bare Fe-Pd NPs, demonstrating the crucial role of PGA in this system. Furthermore, we investigated the dechlorination performance in the presence of different anions. The results indicated that Fe-Pd@PGA NPs can maintain high activity in the presence of Cl − , H 2 PO 4 − , and humic acid, while HPO 4 2− and HCO 3 − ions slightly reduce the dechlorination activity. We believed that PGA is a promising stabilizer and promoter for Fe-Pd NPs and the Fe-Pd@PGA NPs have the potential for practical applications.

Semiconductor Effect from Pd(II) Porphyrin Metal to Its Ligand in Photocatalytic N-Dealkylation

Borong Liao,Junhao Gao,Pei Weng,Linya He,Yusheng Zhang,Qiuhua Liu,Zaichun Zhou

Graphical A semiconductor effect from 4d x 2 − y 2 (Pd) to a 2u (π) orbitals in Pd(II) porphyrin was discovered and a domino relationship from ring distortion, core deformation, band gap variation to photocatalytic activity was established and confirmed. In this work, four saddled Pd(II) porphyrins were developed as photocatalyst for N-dealkylation of triethyl Rhodamine (TER) under visible light, and their catalytic ability was found to be negatively related to the out-of-plane of their macrocycles. Two important relationships involving the metalloporphyrins as catalyst were revealed: (1) a photoexcitative semiconductor effect between the 4d x 2 − γ 2 (Pd) and a 2u (π) orbitals of Pd(II) porphyrin on the dealkylation. (2) a domino process from strap length, ring geometry, core deformation, d-π gap variation, to photocatalytic activity. Two revelations imply a unidirectional electron transfer route from axial ligand, to central metal, to porphyrin ring based on photoexcitation and guide the design and development of complex photocatalysts, and their revelation is attributed to the acquisition of a series of Pd(II) porphyrins with continuous ring distortion. The findings help to understand the photocatalytic single electron transfer (SET)-first mechanism based on metallic complex.

Structured Pd–Cu/NaY Catalyst for Industrial Syngas to DMC: Enhanced Stability and Mechanism

Yu-Qing Li,Yuwei Wang,Fei Wang,Hong Chen,Shenghao Yang,Lihong Zhao,Xu Liang,Yuanli Jiang,Feidong Xie,Liutao Hou,Zhenfeng Liu,Jiantang Sun

A structured, chloride-free Pd–Cu/NaY catalyst was developed for the direct synthesis of dimethyl carbonate (DMC) from syngas-derived methyl nitrite and CO. The NaY zeolite support stabilizes Pd(II) species via strong electrostatic interactions, while Cu addition enhances durability by suppressing Pd reduction and aggregation, as confirmed by H 2 -TPR and TEM. Using shaped spherical supports improves DMC selectivity by limiting methyl nitrite decomposition side reactions through diffusion constraints. Under optimized conditions (CO/MN = 1/6, 120°C), the catalyst achieves a DMC space-time yield of 669 g·kg −1 ·h −1 with high selectivity. A 1000 h stability test shows sustained activity above 550 g·kg −1 ·h −1 after an initial run-in period. In situ DRIFTS studies identify the ligand exchange step as rate-determining and elucidate the full reaction pathway. This robust catalytic system demonstrates strong potential for pilot-scale and industrial syngas-to-DMC processes.

Truncated aptamer-regulated Pd@CeO2 NPs nanozyme activity for colorimetric detection of clenbuterol hydrochloride

Nina Zhao,Xue Cheng,Yu Li,Shuaishuai Wei,Zhouping Wang

Clenbuterol hydrochloride (CLB) is prohibited for use in food-producing animals due to its associated health risks, necessitating the urgent development of facile, highly sensitive on-site detection methods. In this study, a truncated aptamer (C40, Kd = 90.29 nM) with high affinity for CLB was obtained via rational truncation guided by molecular docking. Based on this aptamer, a novel colorimetric aptasensor was constructed, operating on the principle of regulating the peroxidase-mimetic activity of Pd@CeO 2 NPs nanozymes through the aptamer. After the C40 aptamer was adsorbed onto the surface of Pd@CeO 2 NPs via electrostatic interactions, its catalytic activity was significantly suppressed. In the presence of CLB, the specific binding between the aptamer and CLB triggered the dissociation of the aptamer from the nanozyme surface, thereby restoring the catalytic activity and generating a strong colorimetric signal in the TMB-H 2 O 2 chromogenic system. Under the optimized conditions, the aptasensor exhibited a wide linear detection range for CLB from 0.01 to 1000 ng/mL, with a limit of detection as low as 8.2 pg/mL, and demonstrated high specificity against structural analogs and other common interferents. In spiked pork samples, the recovery rates of the developed aptasensor ranged from 98.7% to 101%, with relative standard deviations below 4.69%, outperforming commercial ELISA kits. The strategy of “rational truncation of aptamers for regulating nanozyme activity” provided a new avenue for developing high-performance biosensors targeting small molecules.