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Methanol-to-olefins (MTO) is industrially applied to produce ethylene and propylene using methanol converted from coal, synthetic gas, and biomass. SAPO-34 zeolites, as the most efficient catalyst in MTO process, are subject to the rapid deactivation due to coke deposition. Recent work shows that steam regeneration can provide advantages such as low carbon dioxide emission and enhanced light olefins yield in MTO process, compared to that by air regeneration. A kinetic study on the steam regeneration of spent SAPO-34 catalyst has been carried out in this work. In doing so, we first investigated the effect of temperature on the regeneration performance by monitoring the crystal structure, acidity, residual coke properties and other structural parameters. The results show that with the increase of regeneration temperature, the compositions of residual coke on the catalyst change from pyrene and phenanthrene to naphthalene, which are normally considered as active hydrocarbon pool species in MTO reaction. However, when the regeneration temperature is too high, nitrogen oxides can be found in the residual coke. Meanwhile, as the regeneration temperature increases, the quantity of residual coke reduces and the acidity, BET surface area and pore structure of the regenerated samples can be better recovered, resulting in prolonging catalyst lifetime. We have further derived the kinetics of steam regeneration, and obtained an activation energy of about 177.8 kJ·mol−1. Compared that with air regeneration, the activation energy of steam regeneration is higher, indicating that the steam regeneration process is more difficult to occur.

Cucurbitacin B (CuB) is a widely available triterpenoid molecule that exhibits various biological activities. Previous studies on the anti-tumour mechanism of CuB have mostly focused on cell apoptosis, and research on the ferroptosis-inducing effect has rarely been reported. Herein, we first discovered the excellent cytotoxicity of CuB towards human nasopharyngeal carcinoma cells and elucidated its potential ferroptosis-inducing mechanisms. Morphology alterations of mitochondrial ultrastructure, as observed via transmission electron microscopy, showed that CuB-treated cells undergo ferroptosis. CuB caused intracellular accumulation of iron ions and depletion of glutathione. Detailed molecular mechanism investigation confirmed that CuB both induced widespread lipid peroxidation and downregulated the expression of GPX4, ultimately initiating a multipronged mechanism of ferroptosis. Furthermore, CuB exhibited anti-tumour effects in vitro by inhibiting cellular microtubule polymerization, arresting cell cycle and suppressing migration and invasion. Finally, CuB significantly inhibited tumour progression without causing obvious side effects in vivo. Altogether, our study highlighted the therapeutic potential of CuB as a ferroptosis-inducing agent for nasopharyngeal cancer, and it provided valuable insights for developing effective anti-tumour agents with novel molecular mechanisms derived from natural products.

Methanol-to-olefins (MTO), the most important catalytic process producing ethylene and propylene from non-oil feedstocks (coal, natural gas, biomass, CO2, etc.), is hindered by rapid catalyst deactivation due to coke deposition. Common practice to recover catalyst activity, i.e. removing coke via air combustion or steam gasification, unavoidably eliminates the active hydrocarbon pool species (HCPs) favoring light olefins formation. Density functional theory calculations and structured illumination microscopy reveal that naphthalenic cations, active HCPs enhancing ethylene production, are highly stable within SAPO-34 zeolites at high temperature. Here, we demonstrate a strategy of directly transforming coke to naphthalenic species in SAPO-34 zeolites via steam cracking. Fluidized bed reactor-regenerator pilot experiments show that an unexpectedly high light olefins selectivity of 85% is achieved in MTO reaction with 88% valuable CO and H2 and negligible CO2 as byproducts from regeneration under industrial-alike continuous operations. This strategy significantly boosts the economics and sustainability of MTO process., Methanol-to-olefins is hindered by rapid catalyst deactivation due to coke deposition. Here the authors demonstrate an approach of directly transforming coke to active intermediates to simultaneously recover catalyst activity and boost light olefins selectivity.

In industrial catalytic processes, coke deposition can cause catalyst deactivation by covering acid sites and/or blocking pores. The regeneration of deactivated catalysts, thereby removing the coke and simultaneously restoring the catalytic activity, is highly desired. Despite various chemical reactions and methods are available to remove coke, developing reliable, efficient, and economic regeneration methods for catalytic processes still remains a challenge in industrial practice. In this paper, the current progress of regeneration methods such as oxidation (air, ozone and oxynitride), gasification (carbon dioxide and water steam), and hydrogenation (hydrogen) is reviewed, which hopefully can shed some light on the design and optimization of catalysts and the related processes.

Control of product selectivity is a central yet challenging issue in catalysis chemistry, both in academia and industry. The ever-increasing market demand for ethene, together with relatively low ethene selectivity, necessitates the upgrading of the current methanol-to-olefins (MTO) industry to enhance ethene selectivity. We report here an operable strategy, 1-butene “precoking” technology, by which ethene selectivity has been unprecedentedly enhanced while the catalyst lifespan has been conserved. We also made effects to provide more insight into the long-standing controversies regarding the mechanistic origin of the increase in ethene selectivity. With the aid of a 12C-/13C-methanol switch experiment, MD calculations, and FTIR analysis, it was demonstrated that ethene increase is neither simply—or solely—caused by the configurational diffusion effect, nor due to the transition-state shape selectivity or methylnaphthalene species, but rather to the spatial siting of the presituated “coke”. The relatively evenly distributed presituated coke extends the reaction zone toward the near-core of the SAPO-34 crystal, elongating the diffusion trajectories of molecules and allowing more acid sites to be utilized. The diffusion-hindered higher olefinic intermediates tend to evolve to active aromatic species, which, in turn, lead substantially to ethene. This mechanistic understanding could be also applicable to explaining ethene increase with time on stream (TOS) on parent SAPO-34.

The methanol-to-olefins (MTO) reaction over the SAPO-34 catalyst suffers rapid deactivation due to coke deposition. Here, partial regeneration methods with air combustion and steam gasification were investigated. The results showed that both methods could not only reactivate the spent SAPO-34 catalyst but also prompt ethylene selectivity. Whereas, steam gasification was more effective , by which the initial ethylene selectivity could reach 53%, much higher than that of 23% over fresh SAPO-34 catalyst. Several characterizations, e.g., Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry, indicated that methylated benzenes, which were active hydrocarbon pool species and prompted ethylene selectivity, presented as the main species of residual coke in the SAPO-34 catalyst regenerated via steam gasification. Meanwhile, oxygenated compounds and naphthalene, which could accelerate catalyst deactivation, were observed in the SAPO-34 catalyst partially regenerated via air combustion. Th...

The discharge of spent sulfuric acid generates significant toxic wastes and poses serious hazards to the environment. The effective treatment of spent sulfuric acid remains a great challenge because conventional thermochemical pyrolysis is limited by energy-intensive processing, high equipment investment, and severe equipment corrosion. In this study, we propose an energy-efficient and moderate catalytic oxidation reaction to treat spent sulfuric acid. During the catalytic oxidation reaction, the organic pollutants, especially refractory acid-soluble oil (ASO), in the conversion of spent sulfuric acid and ammonia wastewater were oxidized and degraded into CO2, H2O, and inorganic structures with H2O2 as the oxidant and ozone-treated activated carbon (OAC), derived from coconut shells, as a catalyst. The catalytic activity of OAC enhanced the degradation efficiency of organic pollutants under mild conditions, which was ascribed to the abundant acidic functional groups, and the anchored metal ions on the OAC promoted the generation of highly reactive radicals. The purified (NH4)2SO4 solution with an ASO removal of 96.4% and total organic carbon (TOC) removal of ~92% under the optimum conditions was used to prepare the qualified (NH4)2SO4 product. This work demonstrates the effective utilization of spent sulfuric acid and a cost-effective route to prepare catalysts from agricultural waste for the oxidative degradation of organic pollutants.

This study investigated the catalytic cracking of the microalga Isochtysis zhanjiangensis over a modifled ZSM-5 catalyst with the aim of producing C2-C4 light olefins. Compared with the thermal cracking process, the catalytic cracking of this microalga displayed higher selectivity for and greater yield of these olefins. The catalytic cracking of extracted lipids and the corresponding residues of the microalga was also examined, and the results showed that the lipids could be efficiently converted to light olefins. The catalytic cracking of lipids extracted by different solvents demonstrated that neutral lipids gave the highest yield of light olefins at 36.7%. The yields of light olefins obtained from catalytic cracking of the extraction residues were much lower than the yields obtained from lipids, and thus the lipids, especially the neutral lipids, are the primary contributors to the generation of light olefins. Isochrysis zhanjiangensis with an elevated neutral lipid content will therefore give the highest yield of light olefins through catalytic cracking. (C) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published.by Elsevier B.V. All rights reserved.

High-throughput screening of HZSM-5 supported metal-oxides catalysts were carried out for the coupling reaction of methane with CO to aromatics in a multi-stream reactor system. Zn/HZSM-5 and Mo/HZSM-5 were observed to be rather effective for the catalytic formation of aromatics from the coupling reaction of methane with CO. Temperature-programmed reaction has further proven the efficiency of the coupling of methane and CO over Zn/HZSM-5 catalyst. The results were also validated in a conventional fixed-bed reactor coupled with GC. The results propose that the coupling methane with CO toward benzene and naphthalene can be catalyzed by Zn/HZSM-5 at 500 °C. Both methane and CO are needed for the formation of reactive coke on the catalyst, and the reactive coke may be the initial product in the producing of hydrocarbons.

The C-7 chiral centre in paclitaxel is subject to epimerization under physiological conditions, thus making 7-epi-paclitaxel as the principal degradant. This study was designed to characterize the cytochrome P450 (CYP) enzymes involved in 7-epi-paclitaxel metabolism, and to examine possible metabolic interactions that this C-7 epimer may have with paclitaxel. In human liver microsomes, 7-epi-paclitaxel was oxidized to two monohydroxylated metabolites while the metabolic sites occurred at the C-13 side-chain for M-1 and taxane core ring for M-2. A combination of correlation analysis, chemical inhibition studies, assays with recombinant CYPs, and enzyme kinetics indicated that M-1 was generated predominantly by CYP3A4 and M-2 by CYP2C8. Co-incubation of 7-epi-paclitaxel with paclitaxel in human liver microsomes resulted in potent inhibition of 6alpha-hydroxypaclitaxel formation (IC((50)) = 2.1 +/- 0.2 muM), thus decreasing the metabolic elimination of paclitaxel. In conclusion, both CYP3A4 and CYP2C8 play a major role in biotransformation of 7-epi-paclitaxel in human liver microsomes. The existence of epimeric interactions between paclitaxel and its degradant might be a noteworthy factor resulting in the complex pharmacokinetic profile of paclitaxel.

This paper investigated the process of catalytic pyrolysis of lipid-rich microalga Chlorella pyrenoidosa for the production of light olefins (ethylene, propylene and butene). A modified ZSM-5 zeolite catalyst was used in the reactions, and it had high selectivity for the light olefins production. The catalytic pyrolysis performances of microalga Chlorella pyrenoidosa in nitrogen and steam reaction atmospheres were investigated. The catalytic pyrolysis performances in one-step and two-step processes were investigated and compared. The effects of reaction temperatures and water flow rates on the catalytic pyrolysis performances were also explored. The results showed that higher yield of light olefins was obtained in the steam reaction atmosphere as compared with that in the nitrogen atmosphere. The carbon yield of light olefins obtained from two-step catalytic pyrolysis was nearly three times that from one-step catalytic pyrolysis. The two-step catalytic pyrolysis process also facilitated the production of aromatic hydrocarbons in the liquid products. The maximum carbon yield of light olefins could reach 31.9% in the two-step process under the reaction temperature of 923 K and water flow rate of 30 ml h−1.