In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,...In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,including XRD,N_(2) adsorptiondesorption,TEM,XPS,H2TPR and TG.The results show that the existence of LaAlO_(3) perovskite can enhance the dispersion and sintering resistance of metal nanoparticles and facilitate the transfer of carbon deposits from active sites to the support.Interestingly,the perovskite nanoparticles can also inhibit the reduction of CuOx and the formation of PtCu alloys,resulting in the suitable interaction between Pt and Cu.The PtCu/LaAlO_(3)/SiO_(2)catalyst exhibits the optimal dehydrogenation performance with an isobutane conversion of 47%and isobutene selectivity of 92%after 310 min reaction,which was ascribed to the unique role of LaAlO_(3) perovskite as well as the appropriate PtCu interaction.展开更多
The post-peak deformation of rock is nonlinear,accompanied by strain-softening,dilatancy,and plastic flow.Hence,it is important to better understand these aspects to accurately capture the post-peak deformation behavi...The post-peak deformation of rock is nonlinear,accompanied by strain-softening,dilatancy,and plastic flow.Hence,it is important to better understand these aspects to accurately capture the post-peak deformation behavior.In this study,the developments of rock dilatancy models are reviewed,and it is seen that three major types of models,i.e.,constant dilation angle models,constant rate dilation models,and variable dilation angle models,exist.Using Beishan granite as an example,the dilatancy response of the rock in different deformation stages under uniaxial and triaxial compressions is examined.Furthermore,the variations of the dilation angles under different confiningpressures and plastic shear strains are analyzed,and a segmented confinementand plastic-shear-strain-dependent dilation angle model is proposed.In addition,a plastic-shear-strain-dependent cohesion and friction angle model,named the cohesion-weakening and friction-weakening(CWFW)model,is developed.Finally,the proposed models are implemented into FLAC,and numerical simulations are conducted.The simulation results are compared with laboratory test data with good agreement,indicating that the proposed models can capture the post-peak strain-softening and dilatancy deformation behaviors of brittle rock well.展开更多
基金the National Natural Science Foundation of China(21776214)and State Key Laboratory of Chemical Resource Engineering.
文摘In this study,isobutane dehydrogenation to isobutene reaction was carried out in a series of PtCu bimetallic catalysts prepared by coimpregnation method.The catalysts were characterized by means of several techniques,including XRD,N_(2) adsorptiondesorption,TEM,XPS,H2TPR and TG.The results show that the existence of LaAlO_(3) perovskite can enhance the dispersion and sintering resistance of metal nanoparticles and facilitate the transfer of carbon deposits from active sites to the support.Interestingly,the perovskite nanoparticles can also inhibit the reduction of CuOx and the formation of PtCu alloys,resulting in the suitable interaction between Pt and Cu.The PtCu/LaAlO_(3)/SiO_(2)catalyst exhibits the optimal dehydrogenation performance with an isobutane conversion of 47%and isobutene selectivity of 92%after 310 min reaction,which was ascribed to the unique role of LaAlO_(3) perovskite as well as the appropriate PtCu interaction.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52304081,42177169)the China Postdoctoral Science Foundation(Grant No.2023M740546).
文摘The post-peak deformation of rock is nonlinear,accompanied by strain-softening,dilatancy,and plastic flow.Hence,it is important to better understand these aspects to accurately capture the post-peak deformation behavior.In this study,the developments of rock dilatancy models are reviewed,and it is seen that three major types of models,i.e.,constant dilation angle models,constant rate dilation models,and variable dilation angle models,exist.Using Beishan granite as an example,the dilatancy response of the rock in different deformation stages under uniaxial and triaxial compressions is examined.Furthermore,the variations of the dilation angles under different confiningpressures and plastic shear strains are analyzed,and a segmented confinementand plastic-shear-strain-dependent dilation angle model is proposed.In addition,a plastic-shear-strain-dependent cohesion and friction angle model,named the cohesion-weakening and friction-weakening(CWFW)model,is developed.Finally,the proposed models are implemented into FLAC,and numerical simulations are conducted.The simulation results are compared with laboratory test data with good agreement,indicating that the proposed models can capture the post-peak strain-softening and dilatancy deformation behaviors of brittle rock well.
