Microinterface intensification in hydrogenation and air oxidation processes

Hydrogenations and air oxidations usually have low apparent reaction rate,generally controlled by mass transfer rate,and widely exist in the modern chemical manufacturing process.The key to increase the mass transfer rate is the reduction of the liquid film resistance 1/kLa.In this work,the original concept of microinterface intensification for mass transfer and then for these reactions has been proposed.We derived the regulation model and set up the mathematical calculation method of micron-scale gas-liquid interface structure on mass transfer and reaction,designed the mechanical energy exchange device that can produce gas-liquid microinterface system on a large scale,and established the OMIS system which is able on line to measure the diameter and distribution of millions of microbubbles,interface area a and mass transfer film thicknessδM,as well as developed a series of microinterface intensified reactor systems(MIRs)for the applications of hydrogenation and air oxidation processes.It is believed that this research will provide an up-to-date development for the intensification of hydrogenation and air oxidation reactions.

Loading capacity and emulsification phenomena of HREE extraction by dialkylphosphinic acids with different β,γ,δ-substituents

The relationship between dialkylphosphinic acid structure and their loading capacity for HREEs and emulsification phenomena has rarely been studied.In this paper,we took Lu extraction as an example to study the effect of β,γ,δ-substituents of dialkylphosphinic acids on their loading capacity and anti-emulsification performance for HREEs.To discuss conveniently,the dialkylphosphinic acids were classified into two groups:β-substituent group(P208,INET-1,P218,USTB-1 and P227)and γ,δ-substituent group(P218,P2132 and Cyanex 272).For β-substituent group extractants,their loading capacities are in the order P208(299.7 mg/L)≈INET-1(299.5 mg/L)>P218(270.8 mg/L)>>USTB-1(163.1 mg/L)>P227(151.4 mg/L),while their anti-emulsification/gelation performances are just in the opposite order P227>USTB-1>P218>P208≈INET-1 under the studied conditions.For γ,δ-substituent group extractants,their loading capacities are in the order P218(270.8 mg/L)>P2132(192.3 mg/L)>Cyanex272(131.7 mg/L),while the anti-emulsification performance of P218 is better than those of P2132 and Cyanex 272.The loading capacity data given in the parentheses are obtained through repeatedly extracting Lu from ~4×10^(-4)mol/L of Lu aqueous feed solution with initial pH of 2.40 by 0.01 mol/L extractant at phase ratio A/O of 1:1.

The role ofβ,γ,δ-substituent of dialkylphosphinic acids in HREE extraction and separation behaviors

Heavy rare earth element(HREE)separation has always been a great challenge.The kind of dialkylphosphinic acids is recognized as the third generation of organophosphorous acid extractants.However,detailed relationship betweenβ-substituent(especially when it changes from H to methyl,and further to ethyl)and their extraction behaviors and selectivity for HREEs have rarely been reported.Besides,there are also few reports on effect ofγ,δ-substituent on HREE extraction and separation.In this paper,we synthesized five and collected two dialkylphosphinic acids with differentβ,γ,δ-substituents(from H to ethyl).These extractants were divided into two groups to discuss their extraction behaviors and selectivity for HREEs:β-substituent group(P208,INET-1,P218,USTB-1 and P227)andγ,δ-substituent group(P218,P2132 and Cyanex 272).To evaluate and compare their extractabilities,P507 was used as a reference and Tm,Yb,Lu were extracted with 0.01 mol/L of these extractants from single Tm,Yb and Lu solutions(~4×10^(-4)mol/L)at different initial pH.Besides,pH_(0.5)(Tm),pH_(0.5)^(Yb)and pH_(0.5)^(Lu)values and their differences(ΔpH_(0.5)^(Tm-Yb),ΔpH_(0.5)^(Yb-Lu),ΔpH_(0.5)^(Tm-Lu))for each extractant were given to roughly evaluate their separation performance for Tm,Yb and Lu.To further investigate the selectivity of these extractants for HREEs,Tb,Dy,Ho,Er,Tm,Yb and Lu were extracted from their mixed solution with initial pH of 4.00 at phase ratio A/O of 2:1,1:1 or 1:2.Their HREE separation performance is mainly discussed based on the adjacent HREE separation factors(β_(N+1/N))and their average value(β_(Tb-Lu)).

FINDING THE TOPOLOGY OF IMPLICITLY DEFINED TWO ALGEBRAIC PLANE CURVES

An algorithm is given for computing in a very efficient way the topology of two real algebraic plane curves defined implicitly.The authors preform a symbolic pre-processing that allows us later to execute all numerical computations in an accurate way.

Driving mechanisms of desertification process in the Horqin Sandy Land—a case study in Zhalute Banner,Inner Mongolia of China

Both natural and human factors contributing to desertification were examined to understand the driving mechanisms of the desertification process in Zhalute Banner,Inner Mongolia of China.The coefficient of variation(CV)and climate departure index(Z)were calculated to examine the fluctuations and trends of interannual variations of temperature and precipitation;TM remote sensing data was extracted to obtain the sandy land area;linear regression analysis was used to analyze climate changes and the socio-economic evolution over the years,and it was also used to standardize the variables,which included annual temperature,annual precipitation,human population,and livestock number,in order to measure the difference in the rate of change between climate and anthropogenic factors.The results showed that there was a rise of about 1.6uC in temperature but no significant change in precipitation from 1961 to 2000,which indicated a short-term climatic trend toward aridity in this area,a condition necessary for desertification.The fraction of precipitation in spring tended to increase whilst the fraction in autumn and winter decreased.Both the human population and livestock population had tripled and the cultivated area had doubled from 1961 to 2000,suggesting that socio-economic factors might have contributed more significantly to the desertification.Between 1988 and 1997,the sandy land area increased by 12.5%,nearly 2.4 times in the farming section.It could be concluded that the driving mechanisms of the desertification processes in Zhalute banner are mainly the policy of cropland expansion and the rising populations of humans and their livestock,which has affected the land use pattern in the past decades.