A series of Pt-based catalysts has been prepared by a chelating-agent-assisted impregnation method, and characterized by N2 adsorption/desorption, XRD, XPS, H2-TPR, NH3-TPD, pyridine-FTIR, CO-DRIFT-IR, Raman, and TG techniques to investigate the influence of organic acids on physicochemical properties. It was found that, except in the case of tartaric acid, organic acid-assisted preparation not only led to higher dispersion of Pt particles in comparison with organic acid-free catalyst PtSn/Al2O3, but also changed the concentration of Lewis acid sites and modified the interaction between the metallic Pt sites and the support. Experiments on the catalytic dehydrogenation of propane have revealed that the optimal dehydrogenation performance, with a propane conversion of 35% and a propylene selectivity of 93%, was obtained over the citric acid-assisted catalyst (PtSn/Al2O3-CA). Lewis acid sites are mainly responsible for activating C–H bonds during the tandem activation–cleavage process, whereas coke deposition and the aggregation of Pt sites are mainly responsible for deactivation of the catalyst.

金刚烷作为二十一世纪重要的新兴精细化工原料,在新材料、现代医药和功能性环保催化剂等领域具有重要用途.本文对金刚烷生产技术和应用现状进行了分析,提出以环保型三氯化铝法作为未来金刚烷生产技术的发展方向;阐述了金刚烷产业发展趋势,提出大力发展盐酸金刚烷胺和金刚烷胺衍生物的思路,并对金刚烷市场进行了分析,得出金刚烷市场前景广阔的结论.本研究对促进我国金刚烷产业健康发展具有较好的参考价值.

The mesoporous Sn-SBA-15 (SSF) with varied pore size from was synthesized by changing the hydrothermal temperature, and used to disperse the PtSn oxides (PtSn/SSF) through a typical incipient wetness impregnation method. The pore size had the profound effects on porosity, particle size, the redox property, dispersion and surface chemical state etc. by applying N2 adsorption/desorption isotherms, XRD, HRTEM, TPR, H2-chemisorption, XPS and in situ CO-DRIFT etc. techniques. The catalytic deactivation was mainly caused by sintering of active phase and coke deposition which was identified and quantified by combining Raman and TG analysis. The optimal pore size in this study was 8 nm, corresponding to the sample PtSn/SSF#8 over which the highest propane conversion of 46.9% and the least coke 16.8 mgC/gcat. were achieved.

Fe, Ni, Mn, and Ti were directly doped into CeO2 lattice by hydrothermal method to form solid solution catalysts. Various techniques including N2 adsorption/desorption, XRD, HRTEM, XPS, H2-TPR, CO2-TPD, O2-TPD, Raman, and thermogravimetric techniques were applied to study the structural evolution under the preparation/reaction conditions. The incorporation of metal elements distorted the lattice, the difference of interaction resulted in the differences of redox, oxygen activity, basicity and surface etc. properties. The catalytic conversion of ethane with CO2 exhibited dry reforming feature on Ni doped ceria because of the in situ formed metallic Ni0, and selective oxidation feature on Fe, Mn and Ti doped samples. The number and activity of lattice oxygen played the dominant role in affecting activity and selectivity. The solid solution catalysts revealed good coke resistance.

金刚烷作为二十一世纪重要的新兴精细化工原料,在新材料、现代医药和功能性环保催化剂等领域具有重要用途。本文对金刚烷生产技术和应用现状进行了分析,提出以环保型三氯化铝法作为未来金刚烷生产技术的发展方向;阐述了金刚烷产业发展趋势,提出大力发展盐酸金刚烷胺和金刚烷胺衍生物的思路,并对金刚烷市场进行了分析,得出金刚烷市场前景广阔的结论。本研究对促进我国金刚烷产业健康发展具有较好的参考价值。

By utilizing scanning transmission electron microscopy with spherical aberration(AC-STEM),combining with H-2-TPR,CO-chemisorption and quasi in situ XAS,we investigated the promotion effect of the noble metal, platinum in cobalt-based Fischer-Tropsch catalysts,and the effect of metal-support interaction was excluded by the use of the chemical inert support, beta-SiC. It was concluded that the Pt promoter improved both the dispersion and reduction of cobalt nanoparticles,which increase the amount of Co-0 active sites,and therefore facilitate the catalytic performance of Fischer-Tropsch synthesis. With the aid of AC-STEM,it was observed that Pt was in atomic dispersion in the form of single atoms and clusters. According to this structure,we speculated that the promotion effect of Pt followed the H-2 dissociation and spillover mechanism. The Pt dispersed on cobalt nanoparticles stimulated the H-2 dissociation on the catalyst to a great extent. On one hand,this favored the reduction of cobalt species,on the other hand,it facilitated the H-2 activation and hydrogen-associated CO dissociation during Fischer-Tropsch synthesis,and thus enhanced the activity of the catalyst and improved the selectivity of saturated hydrocarbons.

3D interconnected porous N-doped carbocatalyst derived from the waste air-laid paper plays as an efficient metal-free catalyst for H2S removal in super-Claus reaction. The honeycomb-like porous nitrogen-doped carbons are fabricated through a facile impregnation of alkaline solution and NH3 post-treatment method. The experiments prove that NH3 post-treatment is an efficient way to improve the catalytic performance, which resulting in outstanding reactivity and stability with highest sulfur formation rate of 496.6 gsulfurkgcat.-1 h-1 and sulfur yield of 86.7 % in feed gas with high concentration (ca. 10,000 ppm) of H2S for selective oxidation. Significantly, the optimized pyridinic-N content and defect degree endow the N-doped porous carbon (NPC700) with highest catalytic activity according to the Raman and XPS results. The high surface area and abundant porous structure also contribute to the high catalytic performance by increasing the exposure degree of active site and offering additional active surface. Based on the XPS, SEM, TEM and EDS mapping results, the N-doped porous carbon are proved to be stable catalysts since the morphology and surface chemical environment remain similar after the oxidative desulfurization process.

Catalytic stability and ethylene selectivity were significantly improved through adding K into Cr-based catalysts in oxidative dehydrogenation of ethane with CO2. A series of K promoted Cr catalysts with different K loading were prepared by impregnation method using Ce-Zr solid solution as support. The porosity, crystalline phase, surface chemical state, lattice oxygen property, redox, basicity etc. were investigated, and the results showed that high content of K would enrich surface Cr6+ and O species through the formation of K2CrO4/K2Cr2O7, which further improved the surface basicity. All of these factors acting to conversion and selectivity should be well coordinated to obtain a good productivity of ethylene. The introduction of K helped the desorption of ethylene from active sites and stabilized the reaction within times on stream of 50 h. The introduction of surface K species suppressed the dry reforming but promoted the selective oxidation to produce ethylene.

The oxidative dehydrogenation of ethane using CO 2 as soft oxidant for the production of ethylene, possesses the features of valorization of light alkane and utilization of greenhouse gas. Although a significant challenge, the control of the reaction extent can provide a potential on‐purpose ethylene technology. In the present paper, CeO 2 is proposed to be a promising catalyst, while the deep oxidation process of dry reforming is preferred. The SiO 2 coated CeO 2 catalyst can render the reaction more selective towards ethylene. Through high sensitivity low energy ion scattering spectroscopy, findings were made that SiO 2 only partially covered CeO 2 in the Si 0.1 CeO 2 sample, in which the ethylene selectivity was 2.7 times as high as that of the bulk CeO 2 based on the same conversion level. Further, density functional theory calculations also demonstrated that the presence of the SiO 2 layer was more conducive to the desorption of ethylene.

Selective oxidation of H2S to sulfur is an efficient process for industrial applications and environmental requirement to reduce the residual H2S in the Claus technology to an ultralow content (<0.1 ppm) before releasing the off-gas into the atmosphere. Recently, numerous research studies have been devoted to the development of highly active, selective and stable catalysts for such fields of application. However, there is usually a trade-off between conversion of H2S and selectivity of S due to the inevitable overoxidation of H2S or S into SO2 on such highly active catalysts. In this contribution, we achieve high selectivity of sulfur for the selective oxidation of H2S without losing conversion by phosphate-modified N-doped three-dimensional (3D) mesoporous carbon/carbon nanotube (N-C/CNT) monolith carbocatalysts. The as-synthesized P-modified N-C/CNT monolith (N-C/CNT-6%P) presents a high sulfur selectivity of 91.3% with an excellent normalized sulfur formation rate (lambda(cat)) of 503 g(sulfur).kg(cat)(-1).h(-1), which is comparable with the most active carbon-based and metaloxide catalysts ever reported. Notably, the P-modified N-C/CNT monolith exhibits extremely high stability even under severe reaction environments with a high partial pressure of oxygen, H2O (50 vol %), and impurity gas (i.e., 50 vol % CO2), indicating the promising potential for the practical application. An in-depth investigation including structure evolution, performance variation and promotion mechanism is conducted from the perspective of interaction between the carbon matrix and -POx. The results indicate that the surface properties of P-modified N-C/CNT are regulated by the interaction between the phenol, pyrrolic, pyridinic N groups and P species after the phosphate modification. The improved selectivity with nearly unchanged conversion could be attributed to the moderate adsorption and activation of O-2 enabled by pyridinic nitrogen sites and the P species interaction, which is evidenced by advanced characterization, kinetic analysis and density functional theory (DFT) simulation.

The decomposition reaction of phosphate rock under the action of microwave plasma was investigated. Phosphate rock and its decomposition products were characterized by x-ray diffraction (XRD), energy disperse spectroscopy (EDS), and chemical analysis. The measurements of electron temperature (T e) and electron density (N e) of plasma plume under atmospheric pressure were carried out using optical emission spectroscopy(OES). The electron temperature (T e) was determined based on the calculation of the relative intensity of the O II (301.91 nm) and O II (347.49 nm) spectral lines. Correspondingly, electron densities were obtained using the Saha ionization equation which was based on the C I (247.86 nm) line and the C II (296.62 nm) line under the assumption of local thermodynamic equilibrium (LTE). The relationship between the relative intensity of the active components and the gas output was studied by the spectrometer. Finally the reaction mechanism of the decomposition of the phosphate rock under the action of the atmospheric pressure microwave plasma was proposed. The results showed that with the increase of CO flow and microwave power, the electron temperature and electron density in the plasma show a decreasing and increasing trend. The CO is dissociated into gaseous carbon ions under the action of microwave plasma, and the presence of gaseous carbon ions promotes the decomposition of the phosphate rock.

MXenes, a novel family of 2D materials, are energy materials that have gained considerable attention, particularly for their catalytic applications in emerging areas such as CO2 and N2 hydrogenation. Herein, for the first time, it is shown that the surface reducibility of Ti3 C2 Tx MXene can be tuned by N doping, which induces a change in the catalytic properties of supported Co nanoparticles. Pristine Co-Ti3 C2 Tx MXene favors CO production during CO2 hydrogenation, whereas CH4 production is favored when the MXene is subjected to simple N doping. X-ray photoelectron spectroscopy and transmission electron microscopy (TEM) reveal that surface rutile TiO2 nanoparticles appear on the Ti3 C2 Tx support upon N doping, which interact strongly with the supported Co nanoparticles. This interaction alters the reducibility of the supported Co nanoparticles at the interface with the TiO2 nanoparticles, shifting the product selectivity from CO to CH4 . This study successfully showcases a practical strategy, based on surface chemistry modulation of 2D MXenes, for regulating product distribution in CO2 hydrogenation.

气体经过等离子体活化后具有很高的化学活性,可以加快化学反应速率.本实验利用微波产生的CO等离子体还原CaSO4,结果表明,激发态CO含量是影响反应速率的重要因素,在CO流量为0.6 L/min,微波输入功率为1350W下,反应温度为875℃,反应12 min,转化率就可达86.01％.

The rational designed defect enriched N-doped nanocarbons present superior activity and stability for H2S selective oxidation.

Carbon nanomaterial-supported Pd nanoparticles (Pd/CNS) are easily prepared and effective heterogeneous catalysts for the Heck reaction. However, the drawbacks of poor stability and lower activities compared to homogeneous catalysts limit their use in industrial applications. Chemical modification of carbon nanotubes (CNTs) by heteroatom doping, has been shown to be an effective way to improve the activities and stabilities of Pd/CNT catalysts. Herein we aimed to understand the role of nitrogen-doped carbon nanotubes (NCNTs) in improving the activity and stability of supported Pd catalysts based on density functional theory (DFT) calculations. The adsorption energies of Pd-n (n = 1-6) clusters were investigated for three different types of NCNTs containing graphitic-N (NNTS), pyridinic-N (NNTY), and pyrrolic-N (NNTL). The activities of Pd/NNTS, Pd/NNTY, and Pd/NNTL as catalysts for the Heck reaction were also studied. The calculations regarding the stability and energies of the various interactions revealed that N-doping the CNT structure had important influences on NCNT activity and stability. It was found that NNTL was the most suitable for loading of Pd to catalyze the Heck reaction. Our results showed that the geometry and electronic structures of the heteroatom-doped CNTs were vital for the stability and activities of the catalysts. This work shows that regulation of the distribution of N-structures in N-doped CNTs could effectively enhance the stability and activities of these catalysts.

Depletion of phosphate ore is one of the important resource crises in the world. The exploration of the transfer regularity of mineral impurities to liquid in the digestion process of phosphate rock is of great significance to the production of agricultural fertilizer. In this paper, the reaction kinetics experiments of iron and aluminum compounds in phosphate ore particles were carried out in the range of temperature 50-70 degrees and phosphoric acid concentration 15-25%. Under the combined temperature and concentration conditions, a large number of experiments were carried out to determine the conversion fraction of impurities, and the relationship between conversion fraction and time was obtained. A novel phenomenon of liquid-solid two-phase reaction kinetics was discovered. That is the negative temperature effect. When acid concentration is higher than the critical point, the reaction conversion fraction increases with increasing temperature, but it decreases with increasing temperature below the critical value. It has been found that this phenomenon is caused by the mutual coupling of the phase transition, mass transfer and chemical reaction in the micro-pores structure, as well as specific solubility characteristics of iron-aluminum phosphate. According to the mechanism analysis, the kinetic model was established, which is in good agreement with the experimental data. It can be used to predict the reaction behavior of iron and aluminum mineral impurities of phosphate rock in phosphoric acid. And the kinetics parameters such as D-pd, gamma, D-cop were thus obtained. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

This work was supported by the National Natural Science Foundation of China (21406039 and 21506174), the Guangdong Natural Science Foundation (2020A1515010490), and the Sichuan Provincial Science and Technology Project (2018GZ0313).

A series of CuxCoy catalysts were successfully synthesized by deposition–precipitation with urea method and their catalytic performance was investigated for methanol decomposition to hydrogen. These as-prepared samples were characterized by ICP-OES, XRD, SEM, BET, H2-TPR and XPS. The characterization results indicate that the bimetallic catalysts exhibit better dispersion and reducibility as compared with the monometallic catalysts, and the strong interaction between copper and cobalt can promote the formation of Cu+. Among the fabricated materials, the Cu0.5Co0.5 presents the best catalytic activity and H2 selectivity. Moreover, its catalytic performance is higher than the commercial catalyst at the same test conditions.

In recent years, the primary greenhouse gas (carbon dioxide) has caused a series of severe issues, such as global warming, climate change, etc. Therefore, CCU, CCS and CCUS technologies have been employed to reduce CO₂ emissions. Through our developed "chemical vapor deposition integrated process (CVD-IP)" using carbon dioxide as the carbon source, CO₂ could be catalytically activated and converted to high-value carbon nanotubes. In this work, methane and carbon dioxide has been applied to synthesize CNTs respectively to compare the difference between conventional CH4 CVD and CO₂ CVD-IP technology using Ni-Mo bimetallic catalysts. In the conventional CH4 CVD technology, the carbon productivity and the thermal stability of CNTs could be improved by changing the Mo content of the catalyst, the better catalytic performance 4% Mo catalyst is selected as model catalyst to apply to CO₂ CVD-IP technology. Moreover, when the weak oxidant CO₂ is the only carbon source in the CVD-IP technology, the carbon yield is 22% and the carbon productivity is 1.98 g/gcat. TG curves and Raman spectroscopy display that the CNTs with better thermal stability and higher degree of graphitization are achieved. TEM confirms that the fewer wall numbers and defects of CNTs are obtained. These characterizations suggest that the high quality CNTs could be achieved by CO₂ CVD-IP technology.

The post-Claus selective catalytic oxidation of H2S reaction in a continuous mode is demonstrated on N-doped 3D mesoporous carbon/carbon nanotube (N-C/CNT) monoliths at a reaction temperature higher than the dew point (>180 degrees C) of elemental sulfur. The N-C/CNT monoliths display a hierarchical open porous framework (an interconnected macroporous-mesoporous network) with abundant active nitrogen species at the surface and controlled macroscopic size and shape which represent prerequisites for operating in gas-phase reactions. Physical parameters such as pore size, structural defects, and surface chemical properties are investigated, and the structure-performance relationship for the selective oxidation of H2S is discussed. The optimized monolith catalyst (N-C/CNT800450) shows an outstanding desulfurization activity in terms of the sulfur formation rate (449 g(sulfur) kg(cat.)(-1) h(-1)), stability (for more than 120 h on-stream time), and selectivity (81.6% sulfur selectivity), which outperforms the current state-of-the-art Fe2O3/SiC catalyst and other reported carbon-based catalyst. Moreover, a superior desulfurization activity could be achieved under either water steam (30 vol %) or dry conditions. Our results show that the excellent catalytic desulfurization performance of our monolithic carbon catalyst could be attributed to a combination of the hierarchical interconnected porous framework and the high active nitrogen species density at the exposed carbon surface.