A series of rare earth metals modified birnessite manganese dioxides(RE-Mn)was synthesized by hydrothermal method and their catalytic degradation of toluene was investigated.Yb-Mn shows the best toluene oxidation acti...A series of rare earth metals modified birnessite manganese dioxides(RE-Mn)was synthesized by hydrothermal method and their catalytic degradation of toluene was investigated.Yb-Mn shows the best toluene oxidation activity with the conversion of T50%and T99%at 196 and 226℃,respectively.The physiochemical characterizations identified that the high catalytic performance and excellent stability of Yb-Mn are mainly associated with its higher molar ratios of Mn^(4+)/Mn^(3+),more lattice oxygen(Olatt),and better mobility of surface adsorbed oxygen(O_(ads)).Moreover,it is confirmed that introduction of Yb into birnessite MnO_(2) facilitates the production of acetic acid at lower temperature.These results can aid the design of high-efficiency manganese oxide catalysts for the catalytic combustion of VOCs.展开更多
In order to study the effects of the confining pressure on the erosion characteristics of the self-resonating cavitating jet under wellbore and deep-water conditions,experiments are conducted on aluminum specimens imp...In order to study the effects of the confining pressure on the erosion characteristics of the self-resonating cavitating jet under wellbore and deep-water conditions,experiments are conducted on aluminum specimens impinged by the organ pipe cavitation nozzle and the conical nozzle with the confining pressure in the range 0 MPa–10.0 MPa.Meanwhile,through the numerical simulation of the collapsing process of the cavitation bubble and the noise test,the cavitation erosion mechanism is analyzed.The experimental results show that the optimal standoff distance and the confining pressure can be obtained for the maximum erosion quantities,and the optimal standoff distance is 5 to 7 times greater than the equivalent nozzle outlet diameter and the confining pressure is about 2.0 MPa.Under the same conditions,the erosion caused by the cavitation nozzle is up to 2 times larger than that caused by the conical nozzle.According to the numerical simulation and the noise test,the cavitation erosion on the aluminum specimens is mostly caused by mechanical forces due to the high-frequency pressure pulse generated during the collapse of cavitation bubbles,while just a small part is caused by micro-jets.展开更多
基金Project supported by the Sichuan Provincial Science and Technology Agency Support Projects(2020YFG0066)。
文摘A series of rare earth metals modified birnessite manganese dioxides(RE-Mn)was synthesized by hydrothermal method and their catalytic degradation of toluene was investigated.Yb-Mn shows the best toluene oxidation activity with the conversion of T50%and T99%at 196 and 226℃,respectively.The physiochemical characterizations identified that the high catalytic performance and excellent stability of Yb-Mn are mainly associated with its higher molar ratios of Mn^(4+)/Mn^(3+),more lattice oxygen(Olatt),and better mobility of surface adsorbed oxygen(O_(ads)).Moreover,it is confirmed that introduction of Yb into birnessite MnO_(2) facilitates the production of acetic acid at lower temperature.These results can aid the design of high-efficiency manganese oxide catalysts for the catalytic combustion of VOCs.
基金Project supported by the Open Foundation of China State Key Laboratory of Offshore Oil Exploitation(Grant No.CCL2015RCPS0229RNN)the National Natural Science Foundation of China(Grant No.51274235)+1 种基金the Shandong Provincial Natural Science Foundation(Grant No.ZR2019MEE120)the Major project of CNPC(Grant No.ZD2019-183-005).
文摘In order to study the effects of the confining pressure on the erosion characteristics of the self-resonating cavitating jet under wellbore and deep-water conditions,experiments are conducted on aluminum specimens impinged by the organ pipe cavitation nozzle and the conical nozzle with the confining pressure in the range 0 MPa–10.0 MPa.Meanwhile,through the numerical simulation of the collapsing process of the cavitation bubble and the noise test,the cavitation erosion mechanism is analyzed.The experimental results show that the optimal standoff distance and the confining pressure can be obtained for the maximum erosion quantities,and the optimal standoff distance is 5 to 7 times greater than the equivalent nozzle outlet diameter and the confining pressure is about 2.0 MPa.Under the same conditions,the erosion caused by the cavitation nozzle is up to 2 times larger than that caused by the conical nozzle.According to the numerical simulation and the noise test,the cavitation erosion on the aluminum specimens is mostly caused by mechanical forces due to the high-frequency pressure pulse generated during the collapse of cavitation bubbles,while just a small part is caused by micro-jets.
