Effects of impregnation sequence on the NH3-SCR activity and hydrothermal stability of a Ce-Nb/SnO2 catalyst.

Hydrothermal stability is crucial for the practical application of deNOx catalyst on diesel vehicles, for the selective catalytic reduction of NOx with NH3 (NH3-SCR). SnO2-based materials possess superior hydrothermal stability, which is attractive for the development of NH3-SCR catalyst. In this work, a series of Ce-Nb/SnO2 catalysts, with Ce and Nb loading on SnO2 support, were prepared by impregnation method. It was found that, the NH3-SCR activities and hydrothermal stabilities of the Ce-Nb/SnO2 catalysts significantly varied with the impregnation sequences, and the Ce-Nb(f)/SnO2 catalyst that firstly impregnated Nb and then impregnated Ce exhibited the best performance. The characterization results revealed that Ce-Nb(f)/SnO2 possessed appropriate acidity and redox capability. Furthermore, the strong synergistic effect between Nb and Sn species stabilized the structure and maintained the dispersion of acid sites. This study may provide a new understanding for the effect of impregnation sequence on activity and hydrothermal stability and a new environmental-friendly NH3-SCR catalyst with potential applications for NOx removal from diesel and hydrogen-fueled engines.

Insight into the mechanisms of activity promotion and SO2 resistance over Fe-doped Ce-W oxide catalyst for NOx reduction.

Ceria-based catalysts for the selective catalytic reduction of NOx with NH3 (NH3-SCR) are always subject to deactivation by sulfur poisoning. In this study, Fe-doped Ce-W mixed oxides, which were synthesized by the co-precipitation method, improved the SCR activity and SO2 durability at low temperatures of undoped Ce-W oxides. The improved low-temperature activity was mainly due to the enhancement of redox properties at low temperatures and more active oxygen species, together with the adsorption and activation of more abundant NOx species, facilitating the "fast SCR" reaction. In the presence of SO2, doping with Fe species effectively prevented sulfate deposition on the CeW catalyst, due to the interaction between Fe, Ce, and W species inducing electron transfer among different metal sites and altering the electron distribution. The competitive adsorption behavior between NO and SO2 was changed by Fe doping, in which the adsorption and oxidation of SO2 were restrained. Besides, the elevated NO oxidation accelerated the decomposition of ammonium bisulfate, causing the SCR reaction to not be greatly suppressed. Hence, Fe-doped Ce-W oxides catalysts showed excellent sulfur resistance. This study provides an in-depth understanding of efficient Ce-based catalysts for SO2-tolerance strategies.

[Innovation and development of Chinese Osteosynthesis].

Chinese Osteosynthesis is a fracture treatment system of integrated Traditional Chinese medicine and Western medicine.Starting from our country reality, according to the traditional theory, highlight the characteristics of traditional Chinese medicine and using modern science and technology, under the guidance of the new fracture treatment principles, after a lot of clinical practice and continuous summary, the integrated Chinese and western medicine fracture treatment system with manual reduction and local external fixation is formed.This paper systematically reviews its development history, which provides enlightenment for our innovation and development today.

Hydrothermal Aging Treatment Activates V2O5/TiO2 Catalysts for NOx Abatement.

Thermal stability is crucial for the practical application of deNOx catalysts. Vanadia-based catalysts are widely applied for the selective catalytic reduction of NOx with NH3 (NH3-SCR). Generally, hydrothermal aging at high temperatures induces the deactivation of deNOx catalysts. However, in this work, a remarkable increase in low- and medium-temperature NH3-SCR activity was observed for a V2O5/TiO2 catalyst after hydrothermal aging treatment, especially at 750 °C for 16 h. After the vanadia-based catalyst was hydrothermally treated at 750 °C, the specific surface area decreased and the surface VOx density and surface V ratio increased significantly. Therefore, the aged catalyst presented more abundant polymeric vanadyl species than the fresh one. Furthermore, the redox capability was improved markedly after hydrothermal treatment due to the strong interaction of vanadia and titania, contributing to the NH3-SCR reaction. 750 °C is the optimal temperature to activate the V2O5/TiO2 catalyst, improving the SCR performance significantly. This study provides an in-depth understanding of vanadia-based catalysts for practical applications.

Reaction Pathways of Standard and Fast Selective Catalytic Reduction over Cu-SSZ-39.

Cu-SSZ-39 exhibits excellent hydrothermal stability and is expected to be used for NOx purification in diesel vehicles. In this work, the selective catalytic reduction (SCR) activities in the presence or absence of NO2 were tested over Cu-SSZ-39 catalysts with different Cu contents. The results showed that the NOx conversion of Cu-SSZ-39 was improved by NO2 when NO2/NOx = 0.5, especially for the catalysts with low Cu loadings. The kinetic studies showed two kinetic regimes for fast SCR from 150 to 220 °C due to a change in the rate-controlling mechanism. The activity test and diffuse reflectance infrared Fourier transform spectra demonstrated that the reduction of NO mainly occurred on the Cu species in the absence of feed NO2, and when NO2/NO = 1, NO could react with NH4NO3 on the Brønsted acid sites in addition to undergoing reduction on Cu species. Thus, NO2 can promote the SCR reaction over Cu-SSZ-39 by facilitating the formation of surface nitrate species.

Adsorption-Induced Active Vanadium Species Facilitate Excellent Performance in Low-Temperature Catalytic NOx Abatement.

Vanadia-based catalysts have been widely used for catalyzing various reactions, including their long-standing application in the deNOx process. It has been commonly considered that various vanadium species dispersed on supports with a large surface area act as the catalytically active sites. However, the role of crystalline V2O5 in selective catalytic reduction of NOx with NH3 (NH3-SCR) remains unclear. In this study, a catalyst with low vanadia loading was synthesized, in which crystalline V2O5 was deposited on a TiO2 support that had been pretreated at a high temperature. Surprisingly, the catalyst, which had a large amount of crystalline V2O5, showed excellent low-temperature NH3-SCR activity. For the first time, crystalline V2O5 on low-vanadium-loading catalysts was found to be transformed to polymeric vanadyl species by the adsorption of NH3. The generated active polymeric vanadyl species played a crucial role in NH3-SCR, leading to remarkably enhanced catalytic performance at low temperatures. This new finding provides a fundamental understanding of the metal oxide-catalyzed chemical reaction and has important implications for the development and commercial applications of NH3-SCR catalysts.

Significant promotion effect of the rutile phase on V2O5/TiO2 catalysts for NH3-SCR.

A large amount of polymeric vanadyl species owing to higher interaction energy between vanadia and anatase than rutile and the synergistic effect of vanadium oxides, anatase and rutile TiO2 contributes to an excellent NH3-SCR activity of the vanadia-based catalysts with high rutile content and low specific surface area.

A superior Fe-V-Ti catalyst with high activity and SO2 resistance for the selective catalytic reduction of NOx with NH3.

A series of Fe-V-Ti oxide catalysts were prepared by a co-precipitation method, among which the Fe0.1V0.1TiOx catalyst showed the optimal NH3-SCR performance and excellent SO2 resistance. Fe0.1V0.1TiOx achieved > 90% NOx conversion at 225-450 °C under a GHSV of 200,000 h-1. When introducing SO2 and H2O to the SCR reaction for 24 h, the NOx conversion maintained a level above 93% at 250 °C. The Raman and Mössbauer spectra showed that FeVO4 and Fe2O3 coexisted on the surface of TiO2. In Fe-V-Ti catalysts, the charge interaction between Fe2O3 and FeVO4 as well as the electronic inductive effect between Fe and V species resulted in the improvement of SCR activity and N2 selectivity at high temperatures. The NH3-SCR process on the Fe0.1V0.1TiOx catalyst mainly followed the Eley-Rideal (E-R) reaction mechanism with gaseous NO reacting with adsorbed NH3 adsorbed species.

The balance of acidity and redox capability over modified CeO2 catalyst for the selective catalytic reduction of NO with NH3.

The effect of acidity and redox capability over sulfuric acid-modified CeO2 catalysts were studied for the selective catalytic reduction of NOx with NH3 (NH3-SCR). The deposition of sulfate significantly enhanced the catalytic performance over CeO2. NOx conversion over 4H2SO4/CeO2 at 230-440 °C was higher than 90%. The strong redox capability of CeO2 could result in unselective NH3 oxidation and decrease high temperatures catalytic activity and N2 selectivity. The deposition of sulfate increased the acidity and weakened the redox capability, and then increased the high temperature NOx conversion and N2 selectivity. An appropriate level of acidity also promoted the activity at 190-250 °C over ceria-based catalysts, and with further increase in the acidity, the SCR activity decreased slightly. Weak redox capability lowered the low-temperature catalytic activity. Excellent SCR activity requires a balance of acidity and redox capability on the catalysts.

Polymeric vanadyl species determine the low-temperature activity of V-based catalysts for the SCR of NO x with NH3.

The structure of dispersed vanadyl species plays a crucial role in the selective catalytic reduction (SCR) of NO with NH3 over vanadia-based catalysts. Here, we demonstrate that the polymeric vanadyl species have a markedly higher NH3-SCR activity than the monomeric vanadyl species. The coupling effect of the polymeric structure not only shortens the reaction pathway for the regeneration of redox sites but also substantially reduces the overall reaction barrier of the catalytic cycle. Therefore, it is the polymeric vanadyl species, rather than the monomeric vanadyl species, that determine the NH3-SCR activity of vanadia-based catalysts, especially under low-temperature conditions. The polymeric vanadia-based SCR mechanism reported here advances the understanding of the working principle of vanadia-based catalysts and paves the way toward the development of low vanadium-loading SCR catalysts with excellent low-temperature activity.

[Clinical application evaluation of Guidelines for Diagnosis and Treatment of Internal Diseases in Traditional Chinese Medicine].

To evaluate the applicability and clinical applications of Guidelines for Diagnosis and Treatment of Internal Diseases in Traditional Chinese Medicine, so as to provide the basis for the revision of the guidelines. This study was completed by the research and promotion base for traditional Chinese medicine(TCM) standard. The methods of applicability evaluation and application evaluation were used in the study. The questionnaires were filled out to evaluate applicability of the guideline, including doctor's familiarity with the guideline,the quality of the guideline, applicable conditions and clinical applications. The prospective case study analysis method was used to evaluate application of the guideline, including evaluation of clinical application compliance and application results(such as clinical effects, safety and economy). There were two parts in the guideline, which were TCM guideline and Western medicine guideline. The results of applicability evaluation showed that there were no obvious differences between TCM guideline and Western medicine guideline in doctor's familiarity with guideline(85.43%, 84.57%) and the use of the guideline(52.10%, 54.47%); the guidelines with good quality, and higher scores in the scope of application and the use of the term rationality(91.94%, 93.35%); the rationality scores of relevant contents in syndrome differentiation and treatment were more than 75%; the applicable conditions were better, and the safety score was the the highest. The comprehensive applicability evaluation showed that the proportion of the application of TCM guideline and Western medicine guideline were 77.73%, 75.46%, respectively. The results of application evaluation showed that there was high degree coincidence between the guideline with its clinical application; except for "other treatment" and "recuperation and prevention" in TCM, other items got high scores which were more than 90%; in the evaluation of application effects, safety of the guideline was best, economy of the guideline was better, and clincal effect was good. The comprehensive application evaluation showed that 75%~80% doctors were satisfied with the guideline. The Guidelines for Diagnosis and Treatment of Internal Diseases in Traditional Chinese Medicine has been widely used in clinical practice, which is of high quality, high degree of clinical application,good safety and economy. But there were some disadvantages of the guideline such as lack of evidence-based medicine and innovation, which is need to be improved constantly in the guideline revision.

Significant Promotion Effect of Mo Additive on a Novel Ce-Zr Mixed Oxide Catalyst for the Selective Catalytic Reduction of NO(x) with NH3.

A novel Mo-promoted Ce-Zr mixed oxide catalyst prepared by a homogeneous precipitation method was used for the selective catalytic reduction (SCR) of NO(x) with NH3. The optimal catalyst showed high NH3-SCR activity, SO2/H2O durability, and thermal stability under test conditions. The addition of Mo inhibited growth of the CeO2 particle size, improved the redox ability, and increased the amount of surface acidity, especially the Lewis acidity, all of which were favorable for the excellent NH3-SCR performance. It is believed that the catalyst is promising for the removal of NO(x) from diesel engine exhaust.