Surface compositions,structures,and acidities of the Mo-Te-Fe-Ni catalysts added with La_2O_3,CeO_2, Pr_6O_(12),Nd_2O_3 and Sm_2O_3 were measured and related with the activities of the catalysts for selective oxidatio...Surface compositions,structures,and acidities of the Mo-Te-Fe-Ni catalysts added with La_2O_3,CeO_2, Pr_6O_(12),Nd_2O_3 and Sm_2O_3 were measured and related with the activities of the catalysts for selective oxidation of olefins.It was found that adding rare earth elements to the Mo-Te catalysts increases obviously their selectivities to methacrolein(MAL),and the yield percentage of MAL changes periodically with the increase of atomic numbers of rare earth elements added,and the highest yield was obtained with the catalyst containing CeO_2.The addition of CeO_2 to 9-component Mo-Te catalyst increases not only the activity of the catalyst, but also its thermostability remarkably.The mechanism of rare earth elements in the catalysts was discussed.展开更多
The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence era desirable real saturable absorber （SA） with high power toleran...The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence era desirable real saturable absorber （SA） with high power tolerance and large modulation depth. Here, we report a type of microfiber-based MoTe2 SA fabricated by the magnetron-sputtering deposition （MSD） method. High-energy wave-breaking free soliton pulses were generated with pulse duration/pulse energy/average output power of 229 fs/2.14 nJ/57 mW in the 1.5 μm regime and 1.3 ps/13.8 nJ/ 212 mW in the 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides. Moreover, this was the first demonstration of a MoTe2-based SA in fiber lasers in the 2 ltm regime, and the pulse energy/output power are the highest in the reported thulium-doped fiber lasers mode locked by two-dlmensional materials. Our results suggest that a microfiber-based MoTe2 SA could be used as an excellent photonic device for ultrafast pulse generation, and the MSD technique opens a promising route to produce a high-performance SA with high power tolerance and large modulation depth, which are beneficial for high-energy wave-breaking free pulse generation.展开更多
A series of MoTe_（0.15）V_（0.1）P_xO_n catalysts supported on the SiC were prepared by incipient wetness impregnation.The addition of P to MoTe_（0.15）V_（0.1）O_n/SiC catalysts improved the catalytic performance o...A series of MoTe_（0.15）V_（0.1）P_xO_n catalysts supported on the SiC were prepared by incipient wetness impregnation.The addition of P to MoTe_（0.15）V_（0.1）O_n/SiC catalysts improved the catalytic performance of selective oxidation from propane to acrolein（ACR）,and the catalyst showed highest selectivity（33.7%） and yield（10.7%） when x = 0.05.The MoTe_（0.15）V_（0.1）P_xO_n/SiC catalysts have been characterized by XRD,H_2-TPR,Raman,XPS and NH_3-TPD.The results indicated that a little H_3PMo_（12）O_（40） heteropoly acid and（VO）_2P_2O_7 formed and MoO_3 phase lessened after addition of P.The addition of P promoted the active species dispersed,increased the acidity on the surface,as well as might make the redox process easier.These significant differences improved the activity and selectivity of ACR.展开更多
文摘Surface compositions,structures,and acidities of the Mo-Te-Fe-Ni catalysts added with La_2O_3,CeO_2, Pr_6O_(12),Nd_2O_3 and Sm_2O_3 were measured and related with the activities of the catalysts for selective oxidation of olefins.It was found that adding rare earth elements to the Mo-Te catalysts increases obviously their selectivities to methacrolein(MAL),and the yield percentage of MAL changes periodically with the increase of atomic numbers of rare earth elements added,and the highest yield was obtained with the catalyst containing CeO_2.The addition of CeO_2 to 9-component Mo-Te catalyst increases not only the activity of the catalyst, but also its thermostability remarkably.The mechanism of rare earth elements in the catalysts was discussed.
基金National Natural Science Foundation of China(NSFC)(11704260,61405126,61605122,61775146)Shenzhen Science and Technology Project(JCY20150324141711695,JCYJ20160427105041864,JSGG20160429114438287,KQJSCX20160226194031,JCYJ20160422103744090)+1 种基金Beijing University of Posts and Telecommunications(BUPT)(IPOC2015B003)Natural Science Foundation of Guangdong Province(2016A030310049,2016A030310059)
文摘The pulse energy in the ultrafast soliton fiber laser oscillators is usually limited by the well-known wave-breaking phenomenon owing to the absence era desirable real saturable absorber （SA） with high power tolerance and large modulation depth. Here, we report a type of microfiber-based MoTe2 SA fabricated by the magnetron-sputtering deposition （MSD） method. High-energy wave-breaking free soliton pulses were generated with pulse duration/pulse energy/average output power of 229 fs/2.14 nJ/57 mW in the 1.5 μm regime and 1.3 ps/13.8 nJ/ 212 mW in the 2 μm regime, respectively. To our knowledge, the generated soliton pulses at 1.5μm had the shortest pulse duration and the highest output power among the reported erbium-doped fiber lasers mode locked by transition metal dichalcogenides. Moreover, this was the first demonstration of a MoTe2-based SA in fiber lasers in the 2 ltm regime, and the pulse energy/output power are the highest in the reported thulium-doped fiber lasers mode locked by two-dlmensional materials. Our results suggest that a microfiber-based MoTe2 SA could be used as an excellent photonic device for ultrafast pulse generation, and the MSD technique opens a promising route to produce a high-performance SA with high power tolerance and large modulation depth, which are beneficial for high-energy wave-breaking free pulse generation.
基金supported by the National Natural Science Foundation of China(No20873123)
文摘A series of MoTe_（0.15）V_（0.1）P_xO_n catalysts supported on the SiC were prepared by incipient wetness impregnation.The addition of P to MoTe_（0.15）V_（0.1）O_n/SiC catalysts improved the catalytic performance of selective oxidation from propane to acrolein（ACR）,and the catalyst showed highest selectivity（33.7%） and yield（10.7%） when x = 0.05.The MoTe_（0.15）V_（0.1）P_xO_n/SiC catalysts have been characterized by XRD,H_2-TPR,Raman,XPS and NH_3-TPD.The results indicated that a little H_3PMo_（12）O_（40） heteropoly acid and（VO）_2P_2O_7 formed and MoO_3 phase lessened after addition of P.The addition of P promoted the active species dispersed,increased the acidity on the surface,as well as might make the redox process easier.These significant differences improved the activity and selectivity of ACR.
