Sulfur poisoning mechanism of three way catalytic converter and its grey relational analysis

Combining a detailed catalytic surface reaction mechanism with noble metal and promoter elementary reactions, a new three-way catalytic converter(TWC) reaction mechanism is established. Based on the new mechanism, steady condition numerical simulation is carried out, and the change of light-off temperatures and conversion efficiency with various SO2 contents is obtained. By grey relational analysis(GRA), the relational grade between conversion efficiency and SO2 content is obtained. And, the result shows that SO2 content has the most important influence on C3H6 and NOX conversion efficiency. This provides an important reference to the improvement of activity design of TWC, and may provide guidance for the condition design and optimization of TWC.

Liquid-phase hydrodechlorination of trichloroethylene driven by nascent H_(2)under an open system:Hydrogenation activity,solvent effect and sulfur poisoning

Hydrodechlorination is a promising technology for the remediation of water body contaminated with trichloroethylene(TCE).In this work,the liquid-phase hydrogenation of TCE by Raney Ni(R-Ni)and Pd/C under an open system have been studied,in which nascent H_(2)(Nas-H_(2))generated in situ from the cathode acted as a hydrogen source.Experimental results showed that TCE was completely eliminate from the solution through the synergistic effects of hydrodechlorination and air flotation due to the formation of continuous micro/nano-sized Nas-H_(2)bubbles from the cathode.Furthermore,the effects of inorganic anions and organic solvents on R-Ni and Pd/C hydrogenation activity were investigated,respectively.The results showed that NO_(3)^(-) and acetonitrile can form a competitive reaction with TCE;Sulfur with lone-pair electrons will cause irreversible poisoning to these two catalysts,and have a stronger inhibitory effect on Pd/C.This work helps to realize the separation of volatile halogenated compounds from water environment and provides certain data support for the choice of catalyst in the actual liquid-phase hydrogenation system.

Experimental and computational investigations on the SO_(2) poisoning of(La_(0.8)Sr_(0.2))_(0.95)MnO_(3) cathode materials

To study the formation of detrimental phases under the sulfur gas impurity to the long-term degradation in the cathode material,the classic cathode material,(La_(0.8)Sr_(0.2))_(0.95)MnO_(3)(LSM),was prepared,sintered,and annealed at 800,900,and 1000℃ in the sulfur-containing atmospheres,respectively.Through X-ray diffraction,scanning electron microscope,and transmission electron microscopy techniques,as well as the computer coupling of phase diagrams and thermochemistry methodology,the secondary phases,especially the detrimental ones,under different conditions were predicted and experimentally verified correspondingly.Furthermore,sulfur poisoning results indicate that the accelerated tests might have degradation mechanisms different from actual operation conditions.More importantly,comprehensive comparisons among various impurity-containing conditions were also made to recommend better operation parameters.

Development of nickel based cermet anode materials in solid oxide fuel cells–Now and future

High temperature solid oxide fuel cell(SOFC)is the most efficient and clean energy conversion technology to electrochemically convert the chemical energy of fuels such as hydrogen,natural gas and hydrocarbons to electricity,and also the most viable alternative to the traditional thermal power plants.However,the power output of a SOFC critically depends on the characteristics and performance of its key components:anode,electrolyte and cathode.Due to the highly reducing environment and strict requirements in electrical conductivity and catalytic activity,there are limited choices in the anode materials of SOFCs,particularly for operation in the intermediate temperature range of 500–800C.Among them,Ni-based cermets are the most common and popular anode materials of SOFCs.The objective of this paper is to review the development of Ni-based anode materials in SOFC from the viewpoints of materials microstructure,performance and industrial scalability associated with the fabrication and optimization processes.The latest advancement in nano-structure architecture,contaminant tolerance and interface optimization of Ni-based cermet anodes is presented.And at the end of this paper,we propose and appeal for the collaborative work of scientists from different disciplines that enable the inter-fusion research of fabrication,microanalysis and modelling,aiming at the challenges in the development of Ni-based cermet anodes for commercially viable intermediate temperature SOFC or IT-SOFC technologies.

Effect of barium sulfate modification on the SO2 tolerance of V2O5/TiO2 catalyst for NH3-SCR reaction

Sulfur poisoning of V_2O_5/BaSO_4–TiO_2（VBT）,V_2O_5/WO_3–TiO_2（VWT） and V_2O_5/BaSO_4–WO_3–TiO_2（VBWT） catalysts was performed in wet air at 350℃ for 3 hr,and activities for the selective catalytic reduction of NO_x with NH_3 were evaluated for 200–500℃.The VBT catalyst showed higher NO_x conversions after sulfur poisoning than the other two catalysts.The introduction of barium sulfate contributed to strong acid sites for the as-received catalyst,and eliminated the redox cycle of active vanadium oxide to some extent,which resulted in a certain loss of activity.Readily decomposable sulfate species formed on VBT-S instead of inactive sulfates on VWT-S.These decomposable sulfates increased the number of strong acid sites significantly.Some sulfate species escaped during catalyst preparation and barium sulfate was reproduced during sulfur poisoning,which protects vanadia from sulfur oxide attachment to a great extent.Consequently,the VBT catalyst exhibited the best resistance to sulfur poisoning.