Chemical Reaction Route Selection Based on Green Chemical Engineering

In the preliminary stage of chemical process design, the choice of chemical reaction route is the key design decision, and the concepts of atom utilization and environmental quotient have become extremely useful tools. However, the waste quality such as chemical toxicity and other engineering factors have not been taken into account. Therefore, a synthetic route selection index, Iroute, is proposed to determine the suitability of a chemical route in this paper. Iroute considers the effects of 'extended atom economy', material renewability, chemical characteristics and some engineering factors. The extended atom economy concept regards not only the value of the desired product but also the value of byproducts. The methodology by using Iroute to compare different routes is illustrated in case study of cyclohexanone oxime and acrylonitrile manufacture.

Multi-step Reaction Route Developed for Improving Crystallinity of Boron Nitride Nanoparticles

A multi-step reaction route was developed to synthesize boron nitride（BN） nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanoparticleswas improved via increasing the reaction steps. Meanwhile, a phase transformation from hexagonal BN（hBN） or tur-bostratic BN（tBN） to cubic BN（cBN） occurred, resulting in the increase of cBN content. Moreover, the content ofcBN also slightly increased when the temperature was elevated from 265 ℃ to 280 ℃.

Proton Transfer Mechanism of Alanine Induced by Zn^(2+): a Theoretical Study

In this paper, proton transfer mechanism of alanine induced by Zn2＋ was investiga- ted by the CCSD/6-31＋＋G＊＊//B3LYP/6-31＋＋G＊＊ method. Six neutral complexes and one ampho- teric complex were optimized, among which the amphoteric complex was the most stable with binding energy of 201.92 kcal·mol-1. In addition, the rotation of intramolecular single bond leads to the neutral configuration conversion, in which the rotation energy barriers of C–C single bonds are lower than 10.51 kcal·mol-1, and those of C–O single bonds range among 9.53~17.50 kcal·mol-1. On the other hand, the proton transfers among the carboxylic oxygen atoms can also result in the neutral configuration conversion, whose energy barriers of forward/back reaction are 53.90 and 32.46 kcal·mol-1, respectively. In detail, the proton transfers from carboxylic group to amino lead to their configuration conversion from neutral to amphoteric. Furthermore, under the catalysis of Zn2＋, there was no energy barrier in this reaction. The conversion route from the most stable neutral configuration Ⅱ to the most stable amphoteric configuration I was： Ⅱ→Ⅱ-Ⅲ→Ⅲ→Ⅲ-Ⅵ→Ⅵ→Ⅴ-Ⅵ→Ⅴ→Ⅰ-Ⅴ→Ⅰ,with the energy barrier to be 64.64 kcal·mol-1.

Synthesis and Performance of Li Fe_xMn_(1-x)PO_4/C as Cathode Material for Lithium Ion Batteries

LiFe Mn1-xPO4/C composites were synthesized by a solid-state reaction route using phenolic resin as both reducing agent and carbon source. The effect of Fe doping on the crystallinity and electrochemical performance of LiFexMnt xPOJC was investigated. The experimental results show that the Fe2＋ substitution for Mn2＋ will lead to crystal lattice shrinkage of LiFe Mn1-xPO4/C particles due to the smaller ionic radii of Fe2＋ In the investigated Fe doping range （x = 0 to 0.7）, LiFe Mn1-xPO4/C （x = 0.4） composites exhibited a maximum discharge capacity of 148.8 mAh/g at 0.1 C while LiF%MnI_xPO4/C （x = 0.7） composite showed the best cycle capability with a capacity retention ratio of 99.0% after 30 cycles at 0.2 C. On the contrary, the LiFe Mnl-xPO4/ C （x = 0.5） composite performed better trade-off on discharge capacity and capacity retention ratio, 127.2 mAh/ g and 94.7% after the first 30 cycles at 0.2 C, respectively, which is more preferred for practical applications.

Simultaneous optimization of transit network and public bicycle station network

The traditional manner to design public transportation system is to sequentially design the transit network and public bicycle network. A new public transportation system design problem that simultaneously considers both bus network design and public bicycle network design is proposed. The chemical reaction optimization(CRO) is designed to solve the problem. A shortcoming of CRO is that, when the two-molecule collisions take place, the molecules are randomly picked from the container.Hence, we improve CRO by employing different mating strategies. The computational results confirm the benefits of the mating strategies. Numerical experiments are conducted on the Sioux-Falls network. A comparison with the traditional sequential modeling framework indicates that the proposed approach has a better performance and is more robust. The practical applicability of the approach is proved by employing a real size network.

Experimental and theoretical studies on NO selective catalytic oxidation over α-MnO_(2)

Based on the experimental and theoretical methods,the NO selective catalytic oxidation process was proposed.The experimental results indicated that lattice oxygen was the active site for NO oxide over the α-MnO_(2)(110) surface.In the theoretical study,DFT (density functional theory) and periodic slab modeling were performed on an α-MnO_(2)(110) surface,and two possible NO oxidation mechanisms over the surface were proposed.The non-defectα-MnO_(2)(110) surface showed the highest stability,and the surface Os(the second layer oxygen atoms) position was the most active and stable site.O_(2)molecule enhanced the joint adsorption process of two NO molecules.The reaction process,including O_(2)dissociation and O=N-O-O-N=O formation,was calculated to carry out the NO catalytic oxidation mechanism over α-MnO_(2)(110).The results showed that NO oxidation over the α-MnO_(2)(110) surface exhibited the greatest possibility following the route of O=N-O-O-N=O formation.Meanwhile,the formation of O=N-O-O-N=O was the rate-determining step.

Synthesis,formation mechanism,and intrinsic physical properties of several As/P-containing MAX phases

321 phases are an atypical series of MAX phases,in which A=As/P,with superior elastic properties,fea-turing in the MA-triangular-prism bilayers in the crystal structure.Until now,besides Nb 3 As 2 C,the pure phases of the other 321 compounds have not been realized,hampering the study of their intrinsic prop-erties.Here,molten-salt sintering(MSS)and solid-state synthesis(SSS)were applied to synthesize As/P-containing 321 phases and 211 phases.Analyzing the phase composition of the end-product via multiple-phase Rietveld refinement,we found that MSS can effectively improve the purity of P-containing MAX phases,with the phase content up to 99%in Nb_(3)P_(2)C and 75.4(5)%in Nb 2 PC.In contrast,MSS performed poorly on As-containing MAX phases,only 8.9(4)%for Nb 3 As 2 C and 64(2)%for Nb 2 AsC,as opposed to the pure phases obtained by SSS.The experimental analyses combined with first-principles calculations reveal that the dominant formation route of Nb_(3)P_(2)C is through NbP+Nb+C→Nb_(3)P_(2)C.Moreover,we found that the benefits of MSS on P-containing MAX phases are on the facilitation of three consid-ered chemical reaction routes,especially on Nb 2 PC+NbP→Nb_(3)P_(2)C.Furthermore,the intrinsic physical properties and Fermi surface topology of two 321 phases consisting of electron,hole,and open orbits are revealed theoretically and experimentally,in which the electron carriers are dominant in electrical trans-port.The feasible synthesis methods and the formation mechanism are instructive to obtain high-purity As/P-containing MAX phases and explore new MAX phases.Meanwhile,the intrinsic physical properties will give great support for future applications on 321 phases.