Study on the deactivation and regeneration of the ZSM-5 catalyst used in methanol to olefins

ZSM-5 zeolite catalyst modified by a trace of metal cations shows high activity and high selectivity for the reaction of methanol to olefins （MTO）, but it inclines to deactivate during the reaction. In this paper, the mechanism of the catalyst deactivation and the regeneration method were studied by X-ray diffraction （XRD）, N2 adsorption-desorption, infrared spectra （IR）, and infrared spectra coupled with NH3 molecular probes （IR-NH3）. These characterizations indicated that coke formation was the main reason for the catalyst deactivation. To regenerate the deactivated catalyst, two methods, i.e., calcination and methanol leaching, were used. N2 adsorption-desorption, IR and IR-NH3 characteriza-tions showed that both methods can eliminate coke deposited on the catalyst and make the catalyst reactivated. XRD showed that the structure of the catalyst did not change after regeneration. Interestingly, the regenerated catalyst even showed better catalytic performance of the MTO reaction than the fresh one. Besides, the calcination regeneration can eliminate coke more completely, however, the methanol leaching method can be more easily carried out in situ in the reactor.

In-situ photoisomerization of azobenzene to inhibit ion-migration for stable high-efficiency perovskite solar cells

Ion migration is a notorious problem in perovskite solar cells(PSCs)that severely mutilates device performance.Herein,a strategy to inhibit ion migration in situ is developed by using photoisomerization of azobenzene(AZO)to immobilize cations in the lattice.During the nucleation process,the photoisomerized cis-AZO reacts with FA^(+),MA^(+)and Pb2+cations in the perovskite precursor by synergistic cation-πinteraction and Lewis base coordination,leading to heterogeneous nucleation to produce uniform perovskite film.Meanwhile,it accelerates conversion of intermediate yellowδ-phase to desired black aphase of FAPb I3for improved crystallinity with well-passivated grain surface.Consequently,defect density is effectively reduced for the perovskite film to demonstrate suppressed carrier recombination and enhanced carrier extraction.Subsequently,the solar cell efficiency is elevated from 21.29%to 23.58%with negligible J-V hysteresis.Long-term stability is also improved,with the bare device without any encapsulation retaining 84%of its initial efficiency after aging 744 hours in ambient.

Effect of corrosive media on galvanic corrosion of complicated tri-metallic couples of 2024 Al alloy/Q235 mild steel/304 stainless steel

Galvanic corrosion of tri-metallic couples is more complicated than that of bi-metallic couples. In this study, the effect of the pH of corrosive media on the galvanic corrosion of 2024 A1 alloy/Q235 mild steel/304 stainless steel tri-metallic couples was investigated using potentiodynamic polarization, scanning electron microscopy, scanning vibrating electrode technique and a multi-channel galvanic corrosion meter. The results show that 2024 always acts as the only anode in 3.5 wt% NaCl at pH 5.56,9.72 and 12.0, while both Q235 and 2024 act as anodes at pH 2.39 in the initial stage and then the role of Q235 changes at longer coupling time, which can be attributed to the effect of pH on the surface film of 2024. It is also found that the galvanic current density of a tri-metallic couple is the superposition of two bi-metallic couples when cathodic reactions are controlled by the diffusion of oxygen, otherwise it is smaller than that of the sum of two bi-metallic couples. The localized corrosion instead of uniform corrosion of anodic metal is accelerated by galvanic corrosion.

Nano Calcium-Deficient Hydroxyapatite/O-carboxymethyl Chitosan-CaCl_(2) Microspheres Loadedwith RheinforBone Defect Repair

Glutaraldehyde(GA),the most widely used crosslinking agent for biomaterials,is cytotoxic.CaCl_(2) is of particular interest due to its non-toxic nature.Rhein can chelate Ca^(2+)and promote bone growth.Here we reported a novel nano calcium-deficient hydroxyapatite/O-carboxymethyl chitosan-CaCl_(2) microspheres loaded with rhein(RH-nCDHA/OCMC-CaCl_(2) microspheres)using CaCl_(2) as crosslinking agent for bone defect repair.The obtained microspheres were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetric analysis(TG)and Fourier transform infrared spectroscopy(FT-IR).The surface of the obtained microspheres is rough with quite a few voids.The nano calcium-deficient hydroxyapatite(nCDHA)accounts for about 70% of the total weight of the microspheres,which is equivalent to the proportion of inorganic substances in human bones.A high encapsulation efficiency(EE)and loading capacity(LC)of the microspheres loaded with rhein was 90.20±0.60% and 11.03±0.30%,respectively.For microspheres using CaCl_(2) in simulated body fluid(SBF)after 14 days,the drug released continuously and bone-like apatite formed like layer.The cells on the surface of the RH-nCDHA/OCMC-CaCl_(2) microspheres grew better comparing with nCDHA/OCMC-GA microspheres and the skull defects of rats after landfill can be almost repaired after 8 weeks,which revealed the potential of the microspheres for bone repair.

EETs mediate cardioprotection of salvianolic acids through MAPK signaling pathway

Salvianolic acids,including salvianolic acid A(SAA)and salvianolic acid B(SAB),are.the main water-soluble bioactive compounds isolated from the Chinese medicinal herb Danshen and have been shown to exert in vitro and in vivo cardiovascular protection.Recent studies suggest that epoxyeicosatrienoic acids(EETs),the primary cytochrome P4502J(CYP2J)epoxygenase metabolites of arachidonic acid,are involved in the progression of ischemic injury in diverse organs.Here,we investigated the relation between the protective effects of salvianolic acids and EETs/sEH as well as MAPK signaling pathway.In the present study,the rat acute myocardial infarction(AMI)model was established by the left anterior descending coronary artery occlusion.Our results showed that salvianolic acids significantly reduced ST-segment elevation and serum levels of CK-MB,LDH,and ALT in AMI rats,and significantly attenuated the caspase 3 expression and reduced the ratio of Bax/Bcl-2.ELISA measurement showed that salvianolic acids significantly increased the 14,15-EET levels in blood and heart,and attenuated hydrolase activity of sEH in heart of AMI rat.Western blotting analysis suggested that salvianolic acids significantly attenuated the phosphorylation of JNK and p38,and increased phosphorylation of ERK in heart.In conclusion,these results indicate that EETs/sEH and MAPK signaling pathways are important processes in cardioprotection of salvianolic acids.