Synthesis of hierarchical SAPO-11-based catalysts with Al-based metal-organic framework derivative as mesoporogen to improve n-decane branched isomerization

Hierarchical SAPO-11 molecular sieve(ACS-11) was successfully synthesized employing the Al2O3/carbon(Al_(2)O_(3)/C) composite obtained through the pyrolysis of Al-based metal-organic framework(Al-MOF-96)as mesoporogen.Unlike other carbon-based mesoporogens with strong hydrophobicity,the Al_(2)O_(3)/C interacts with phosphoric acid and generates the AlPO_(4)/C structure,which promotes the Al2O3/C dispersion in the synthesis gel of SAPO-11 and avoids the phase separation between them.The Al_(2)O_(3)/C as mesoporogen decreases the crystallite size of SAPO-11 via preventing the aggregation of SAPO-11crystals.Additionally,the addition of Al_(2)O_(3)/C improves the Si distribution in the ACS-11 framework.Consequently,ACS-11 has smaller crystallites,more mesopores,and a greater amount of medium Bronsted acid centers than the conventional microporous SAPO-11 and the SAPO-11 synthesized using activated carbon as mesoporogen.The corresponding Pt/ACS-11 catalyst exhibits the maximal selectivity to multi-branched C10isomers(23.28%) and the minimal cracking selectivity(15.83%) in n-decane hydroisomerization among these catalysts.This research provides a new approach for preparing hierarchical silicoaluminophosphate molecular sieve-based catalysts to produce high-quality fuels.

Decomposition of Supercritical Linear-Fractional Branching Processes

It is well known that a supercritical single-type Bienayme-Galton-Watson process can be viewed as a decomposable branching process formed by two subtypes of particles: those having infinite line of descent and those who have finite number of descendants. In this paper we analyze such a decomposition for the linear-fractional Bienayme-Galton-Watson processes with countably many types. We find explicit expressions for the main characteristics of the reproduction laws for so-called skeleton and doomed particles.

ANALOG PREDISTORTION LINEARIZER ON REDUCING CORRECTED AMPLITUDE OVERSHOOT

This paper presents a dual-nonlinear branch linearizer for reducing the corrected amplitude overshoot of conventional single nonlinear branch linearizer. Theoretical analysis is carried out, the analysis is verified by simulation, and a prototype of Ka band 25.28~26.08 GHz dual nonlinear branch linearizer is achieved. It indicates that the corrected amplitude overshoot is less than 0.5 dB, the C/I3 improvement is more than 10 dB related to a single carrier IBO 9 dB, when it is linked and tested for 50 W spacebrone Travelling Wave Tube Amplifier(TWTA).

Discrete differential evolution algorithm for integer linear bilevel programming problems

A discrete differential evolution algorithm combined with the branch and bound method is developed to solve the integer linear bilevel programming problems, in which both upper level and lower level variables are forced to be integer. An integer coding for upper level variables is adopted, and then a discrete differential evolution algorithm with an improved feasibility-based comparison is developed to directly explore the integer solution at the upper level. For a given upper level integer variable, the lower level integer programming problem is solved by the existing branch and bound algorithm to obtain the optimal integer solution at the lower level. In the same framework of the algorithm, two other constraint handling methods, i.e. the penalty function method and the feasibility-based comparison method are also tested. The experimental results demonstrate that the discrete differential evolution algorithm with different constraint handling methods is effective in finding the global optimal integer solutions, but the improved constraint handling method performs better than two compared constraint handling methods.

Branch and Bound Algorithm for Globally Solving Minimax Linear Fractional Programming

In this paper,we study the minimax linear fractional programming problem on a non-empty bounded set,called problem(MLFP),and we design a branch and bound algorithm to find a globally optimal solution of(MLFP).Firstly,we convert the problem(MLFP)to a problem(EP2)that is equivalent to it.Secondly,by applying the convex relaxation technique to problem(EP2),a convex quadratic relaxation problem(CQRP)is obtained.Then,the overall framework of the algorithm is given and its convergence is proved,the worst-case iteration number is also estimated.Finally,experimental data are listed to illustrate the effectiveness of the algorithm.

Synthesis of ZSM-22/SAPO-11 composite molecular sieve-based catalysts with small crystallites and superior n-alkane hydroisomerization performance

To improve oil quality,ZSM-22/SAPO-11 composite molecular sieves were synthesized by adding ZSM-22 into a synthetic gel of SAPO-11 for n-decane hydroisomerization.The mass ratios of ZSM-22/(ZSM-22+SAPO-11)in the composite molecular sieves were optimized and the optimal ZSM-22/SAPO-11 composite(ZS-9)was obtained.The electrostatic repulsions between the ZSM-22 precursors and the SAPO-11 crystalline nuclei produced small ZSM-22 and SAPO-11 crystallites in ZS-9,which increased the specific surface area and mesopore volume and thereby exposed more acid sites.In comparison with conventional SAPO-11,ZSM-22 and their mechanical mixture,ZS-9 with smaller crystallites and the optimal medium and strong Brønsted acid centers(MSBAC)content displayed a higher yield of branched C_(10) isomers(81.6%),lower cracking selectivity(11.9%)and excellent stability.The correlation between the i-C_(10) selectivity and the MSBAC density of molecular sieves indicated that the selectivity for branched C_(10) isomers first increased and then decreased with increasing MSBAC density on the molecular sieves,and the maximum selectivity(87.7%)occurred with a density of 9.6×10^(−2)μmol m^(−2).

基于线性化潮流模型的配电网电压无功控制策略

针对现有基于二阶锥松弛的电压无功控制模型无法以电压波动为目标且求解速度较慢等问题,文中提出了一种基于线性化潮流模型的配电网电压无功控制策略。基于支路潮流方程建立了包含有载调压分接头、电容器组和光伏逆变器等调控手段的电压无功控制模型,并将其离散变量松弛为连续变量,以形成二阶锥规划。进一步以二阶锥规划所得结果为基准点构造线性化潮流模型,并以电压波动最小为目标,将连续变量还原为离散变量。最后基于改进的IEEE-33节点测试系统进行了仿真,仿真结果表明所提出的线性化潮流模型具有较高的精度和更快的求解速度,能够适用于配电网实时电压无功控制。

基于投入并联小电阻的含多分支配电网单相接地故障行波测距方法

含多分支配电网拓扑结构复杂,传统算法常忽略分支,测距精度受到影响。为此,提出基于投入并联小电阻的含多分支配电网单相接地故障行波测距方法。首先,检测故障零模、线模波到达首端的时间差,投入消弧线圈处并联小电阻,利用并联小电阻产生的零模波到达首端的时刻,以及零模波到达故障点后折、反射产生的线模波到达首、末端的时刻,消除零模波波速影响。其次,定义故障判别系数,判断故障发生在主干线路或分支上,根据故障所在区段精确计算故障距离,并根据混合线路的特点对故障判别系数进行修正以适应混合线路。最后,在PSCAD仿真平台上对所述方法进行验证,结果表明所提方法可判断故障区段,精确定位故障点且耐受过渡电阻能力和抗同步误差能力强。

Linear/branched Block Polyethylene Produced by a-Diimine Nickel(Ⅱ)Catalyst and Bis(phenoxy-imine)Zirconium Binary Catalyst System in the Presence of Diethyl Zinc

In order to promote development of linear/branched block polyethylenes based on new catalytic systems,we synthesized a novel a.dimine nickel(Ⅱ)complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-Naryl structures.The activity of a-dimine nickl(Ⅱ)catalyst was 3.02x10^(6)g-mol_(ni)^(-1)·h^(-1) at 70℃,and resultant polyethylene possessed 135/1000C branches.The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the a-dimine nicke(Ⅱ)complex/bis(phenoxy-imine)zirconium in the presence of diethyI zinc.With the addition of ZnEtz(from 0 to 400),the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks.The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained vla adjusting ZnEt;equiv.and molar ratio of two catalysts.In addition,the branching degree of the polyethylene increased from 13/1000C to 56/1000 with the increase of the proportion of a dimine nickel(Ⅱ)catalyst.Using this binary catalyst system,the reaction temperature of chain shutting polymerization can be carried out at 70℃,which is more conducive to industrial application.

一种整数线性乘积规划问题的分支定界算法

本文为了求解整数线性乘积规划(ILMP)问题的全局最优解,提出一种新的线性松弛分支定界算法.该算法利用对数函数的单调性及凹凸性,得到(ILMP)全局最小值的下界,并利用区域缩减技术以最大限度地删除不可行区域,加快该算法的收敛速度.最后数值实验表明,本文提出的算法是有效并且可行的.

一类非凸约束二次规划问题的分支定界算法

针对一类非凸约束二次规划问题,提出一种新的参数化线性松弛分支定界算法,主要利用线性松弛技术求得原问题的全局最优值下界,以及区域删除规则缩减不可行区域,证明了算法的收敛性,最后通过数值实验表明算法的收敛速度加快,且该算法有效可行。

全局求解一类线性比式和问题的分支定界算法

针对一类线性比式和规划问题(SLR)提出一种新的分支定界算法.首先通过Charnes-Cooper变换和引进新的变量将该问题转化为等价非线性规划问题(EP).其次在给定子盒子上对问题(EP)非凸约束的凹部分进行线性近似,得到一个凸二次规划问题(SOCR).然后用所提出的算法求问题(SLR)的全局最优解.最后从理论上证明了算法的收敛性和计算复杂度,数值实验表明该算法是可行有效的.

Water-to-air transfer of branched and linear PFOA:Influence of pH,concentration and water type

The volatilisation of perfluorooctanoic acid(PFOA)was measured experimentally at a range of pH values using a previously published laboratory method.Water-to-air transfer was studied for five structural isomers,namely:the linear isomer(n-PFOA)and the four most commonly occurring branched isomers(3-,4-,5-and 6-PFOA).The influence of water concentration and water type on the pH-dependent waterto-air transfer was also investigated for n-PFOA.The water-to-air transfer was studied over the course of 48 h at pH values ranging from 0.2 to 5.5.Under all experimental conditions tested,the volatilisation of PFOA was negligible at pH>2.5.In experiments performed with MilliQ water,volatilisation increased with decreasing water pH.In experiments performed with tap water and lake water,maximum volatilisation was observed at pH 1.The concentration of PFOA in water had no influence on the pH value at which water-to-air transfer was observed(i.e.at pH<2.5)for the concentration range tested(0.1e50 mg/L PFOA in deionised water).Although the percentage of PFOA volatilised was significantly different for the four branched isomers at low pH,volatilisation was not observed above pH 2.5 for any branched isomer suggesting that all PFOA isomers have a low pKa.Overall,these laboratory results demonstrate that volatilisation of any structural isomer of PFOA from water is negligible at environmentally-relevant conditions.It is unlikely that PFOA isomers will be fractionated in the environment as a result of volatilisation because it is a process of negligible environmental relevance.

A comparison study on the melt crystallization kinetics of long chain branched and linear isotactic polypropylenes

The isothermal and non-isothermal crystallization kinetics of LCBPP and linear-iPP was investigated by optical microscopy and differential scanning calorimetry (DSC). The optical microscopy results in the isothermal crystallization process show that the crystals of LCBPP grow slower than the crystals of the linear-iPP. This originates from the low chain mobility, or in other words, the lower chain diffusion rate of LCBPP due to the existence of long side chains. The DSC results in the isothermal crystallization process show that the LCBPP exhibits, however, a higher overall crystallization rate with respect to the linear-iPP. This is related to the higher nucleation ability of LCBPP since the isothermal crystallization process of both LCBPP and linear-iPP are nucleation-dominated. Avrami analysis indicates that the nucleation nature and crystal growth manner of LCBPP and linear-iPP are about the same. The analy- ses of the non-isothermal crystallization processes indicate an increment in crystallization rate with increasing cooling rate. But at any cooling rate, the linear-iPP crystallizes more quickly than the LCBPP. This implies that the non-isothermal crystallization processes of LCBPP and linear-iPP are diffu- sion-dominated, in which the lower chain diffusion rate of LCBPP results in the slower crystallization of it.

考虑纵向动态边端效应的短初级直线感应电机等效电路改进模型

直线感应电机由于纵向动态边端效应的存在,在运行过程中会产生附加损耗和附加力,使得电机性能表现变差。针对该问题,本文从传统等效电路出发,通过在原有励磁支路上添加并联边端效应支路的方式,构建了考虑纵向动态边端效应的短初级直线感应电机等效电路改进模型,并推导了边端效应支路上的电磁参数。试验结果表明,本文提出的等效电路改进模型与传统等效电路相比,推力计算误差更小,验证了本文提出的改进模型准确性。

基于线性混合模型的落叶松枝条长度和角度模型

以黑龙江省五营林业局丽林林场30株人工落叶松2190个枝条长度和角度数据为例,利用逐步回归技术建立落叶松枝条长度和角度模型:BL=b1+b2DINC+b3DINC2+b4DBH·DINC2,BA=b1+b2DINC+b3DINC2+b4DBH·DINC。利用S-PLUS软件中的LME模块,考虑树木效应拟合线性枝条长度和角度模型。采用AIC、BIC、对数似然值和似然比检验等模型评价统计指标对不同模型的拟合效果进行比较分析。结果表明:当拟合枝条长度和角度模型时,b1,b2,b3同时作为混合参数时模型拟合最好。为了描述混合模型构建过程中产生的异方差现象,把幂函数和指数函数加入到枝条长度和角度混合模型中。指数函数显著提高了枝条长度混合模型的拟合效果,幂函数显著提高了角度混合模型的拟合效果,并且消除了异方差现象。模型检验结果表明:混合模型通过校正随机参数值能提高模型的预测精度。因此,混合模型在应用上不但能反映总体枝条长度和角度预测,而且能通过方差协方差结构校正随机参数来反映树木之间的差异。

反相高效液相色谱法分离直链烷基苯磺酸钠同系物和异构体

建立了直链烷基苯磺酸钠的反相高效液相色谱分析方法。探讨了流动相中甲醇含量、电解质浓度及不同电解质对样品保留时间、选择性和分离度等的影响,得到最佳的色谱分离条件为:流动相为甲醇 30mmol/L磷酸二氢钠水溶液,采用折线梯度洗脱,检测波长为226nm。结果表明,该法对烷基链为C8～C16的烷基苯磺酸钠的同系物能完全分离,对烷基苯磺酸钠的异构体有一定的分离能力。

加氢异构化催化剂的研究——酸性能的影响

以具有不同硅/铝摩尔比的ZSM-12和ZSM-22分子筛为研究对象,采用XRD、XRF、N2吸附、吡啶吸附和SEM等分析工具对合成的分子筛样品进行了详细的表征。结果表明,所用分子筛为纯相晶体且Al原子完全处于分子筛骨架中;分子筛Br9nsted酸中心数量和强度随硅/铝摩尔比变化而改变。以正癸烷为模型化合物对制备的催化剂进行加氢异构化反应评价。结果表明,分子筛的酸性中心数量是影响催化剂活性的主要因素;在低转化率(<85%)下,Br9nsted酸中心数量对催化剂异构选择性的影响要大于强Br9nsted酸中心的比例。另一方面,研究结果也表明,即使分子筛酸性质相同,如果分子筛孔径不同,相应催化剂所表现出来的催化活性和选择性也是不相同的。

直链重烷基苯磺酸盐的驱油能力研究

研究了所合成的各种结构的直链烷基苯磺酸盐单剂及其复配体系在不同碱质量分数情况下对大庆四厂油 /水界面张力情况。结果表明 :对同一碳链长度的直链烷基苯磺酸盐 ,带甲基的比带乙基、异丙基和苯环上不带取代基的烷基苯磺酸盐降低界面张力的能力强 ;同样结构的十六碳链长的烷基苯磺酸盐又较其他碳链长度的烷基苯磺酸盐效果更优 ;长、短碳链的带甲基的直链烷基苯磺酸盐按一定比例复配 ,协同效应显著 ;与支链烷基苯磺酸盐复配后 ,体系的驱油能力、抗稀释性和抗Ca2 +、Mg2 +能力明显增加。

催化裂化反应中支链烷烃生成途径的分析

分析了大庆VGO原料在酸性分子筛催化剂上反应时汽油烷烃异构体的产生及转化。烷烃异构体主要是甲基异构体,在反应产物中的量随反应深度增加而增加,表明骨架异构反应主要通过质子化环丙烷中间体(PCP)进行。甲基异构体中主要是单甲基异构体,其次是二甲基异构体,三甲基异构体的比例极少。长支链烷烃主要是通过较大的质子化环烷烃中间体如PCB、PCPe、PCH等生成,而多甲基烷烃则是由单甲基烷烃进一步通过质子化环丙烷中间体生成。