Facile synthesis of efficient pentaethylenehexamine-phosphotungstic acid heterogeneous catalysts for oxidative desulfurization

The ultra-deep desulfurization of oil needs to be solved urgently due to various problems,including environmental pollution and environmental protection requirements.Oxidative desulfurization(ODS)was considered to be the most promising technology.The facile synthesis of highly efficient and stable HPW-based heterogeneous catalysts for oxidative desulfurization is still a challenging task.In this paper,pentamethylene hexamine(PEHA)and phosphotungstic acid(HPW)were combined by a simple one-step method to prepare a heterogeneous catalyst of PEHA-HPW for the production of ultra-deep desulfurization fuel oil.The composite material exhibited excellent catalytic activity and high recyclability,which could reach a 100% dibenzothiophene(DBT)removal rate in 30 min and be recycled at least 5 times.Experiments and DFT simulations were used to better examine the ODS mechanism of PEHA-HPW.It was proved that the rich amino groups on the surface of PEHA-HPW play a crucial role.This work provides a simple and feasible way for the manufacture of efficient HPW-based catalysts.

Reaction kinetics for the heterogeneously resin-catalyzed and homogeneously self-catalyzed esterification of thioglycolic acid with 2-ethyl-1-hexanol

Producing 2-ethyl-1-hexyl thioglycolate(ETE)via esterification reaction with thioglycolic acid(TGA)aqueous solution as raw material by reactive-separation coupling technology is a promising process intensification method.To choose suitable reactive-separation coupling strategy,the kinetic studies of the esterification of TGA with 2-ethyl-1-hexanol(EHL)were carried out in a batch system.The commercial ion exchange resin was employed as an eco-friendly catalyst.The effects of temperature,catalyst concentration and molar ratio were determined.It was interesting to observe that the equilibrium conversion of TGA increased with the increase of catalyst mass fraction due to the adsorption of product water onto resin surface.The activity-based pseudo-homogeneous(PH),Eley-Rideal(ER)and Langmuir-Hinshelwood-Ho ugen-Watson(LHHW)models were used to fit the kinetics data of the resin-catalyzed reaction.The models of ER and LHHW performed better than the PH model.The kinetics of the TGA-self-catalyzed reaction was also determined.An activity-based homogeneous kinetics model could well describe this self-catalyzed reaction.These results would be meaningful to the selection and design of an appropriate reactionseparation strategy for the production of ETE,to realize the process intensification.

Harnessing perennial and indeterminant growth habits for ratoon cotton(Gossypium spp.)cropping

Ratoon is the stub or root of a perennial plant that is commonly retained after harvest to produce a following crop.This paper presents a review of ratoon cotton in relation to a broader framework that has been examining perennialization of agriculture for the benefit of ecology and economy.Cotton is botanically indeterminate,but has been treated as an annual after domestication,yet the habit of perenniality is retained and the plants begin to resprout after the first harvest.In some cropping systems,this tendency is exploited using the“ratooning”practice(i.e.growing one or more crops on the rootstock of the first).Ratooning has declined for various reasons such as an increase in the prevalence of pests and diseases and overwintering risk.However,ratooning has many benefits such as no annual tillage before sowing,a well-established root system,and high yield.The three methods of ratooning offer flexibility to balance the environmental and economic benefits in agriculture.The greatest environmental benefits arise from perennial ratoon cropping of semi-wild cotton,and the greatest economic benefit is obtained from biannually cropping modern annual cultivars.However,an optimum solution would be provided by perennial cropping annual cultivars.To realize both environmental and economic benefits,research is needed in the following main areas:preventing the buildup of pests and diseases,breeding the most suitable cotton cultivars for ratooning,and developing light and simplified cultivation(LSC)systems for ratoon cultivation.