硫酸烧渣氰化法提金前的氨水预处理

硫酸烧渣 (以下简称烧渣 )的综合利用 ,在国外已有专利技术 ,而国内对其综合利用的研究与开发还很不深入 ,目前仅以 2 0～ 30元 /Ｔ的价格卖给水泥厂烧制水泥 ,其有效价值未得到充分的利用。从烧渣中提取黄金是其综合利用的一项重要内容 ,在黄金的工业生产中以氰化法的工艺最为成熟 ,生产成本也最低。但烧渣中含有较高的Ｚｎ、Ｃｕ ,若不预先将其除去而直接进行氰化浸出 ,则每吨烧渣将消耗 1 5～ 1 8ｋｇＮａＣＮ。仅此一项 ,将会导致亏损。Ｃｕ的存在不仅增加ＮａＣＮ的消耗量 ,而且还会使Ａｕ的氰化浸率严重下降。国内在处理富含黄铜矿的…     

应用红外光谱研究脱灰对伊敏褐煤结构的影响

对伊敏褐煤的原煤和脱灰煤进行了红外光谱分析,并通过分段分峰拟合分析了脱灰前后伊敏煤结构的变化。结果表明,脱灰处理对煤中有机结构会产生一定影响。对脂氢和羟基氢键有机结构影响较小,脱灰后,脂氢结构中CH2不对称伸缩振动没有变化,CH伸缩振动明显减少,而CH2对称伸缩振动和CH3不对称伸缩振动略有增加;羟基氢键结构中羟基N羟基、自缔合羟基氢键以及羟基π氢键的强度有所降低,而环氢键和羟基醚氢键的吸收强度有所增加;对芳香结构和含氧官能团的影响较大,芳香结构由原煤中的苯环三取代占主导地位转变为脱灰煤中的苯环三和四取代;含氧官能团中烷基醚和脂肪羧酸脱灰后吸收峰的强度明显减弱,这是由于水解反应导致的,而酚羟基和羧酸脱灰后吸收强度明显增强。     

CuO／γ－Al_2O_3中热稳定助剂作用的探讨

用等量共浸法和分浸法制备了含Ｃａ、Ｓｒ、Ｂａ、Ｍｇ、Ｚｒ和Ｌａ助剂的ＣｕＯ／γ－Ａｌ_２Ｏ_３催化剂（ＣｕＯ／Ａｌ_２Ｏ_３＝８ｗｔ％，Ｍ／Ｃｕ（原子比）＝０．１５，Ｌａ／Ｃｕ＝０．３５）．用ＸＲＤ和ＸＰＳ等考察了在高温７５０℃、９５０℃和１０５０℃老化后的相结构和ＣＯ氧化活性，实验表明所有助剂均有不同程度的抗烧结和抗相变作用。其中Ｌａ、Ｃａ和Ｚｒ的效果最好。分浸法比共浸法好。在９５０℃老化后，ＣｕＡｌ_２Ｏ_４和α－Ａｌ_２Ｏ_３同步产生；随老化温度增高，ＣＯ氧化活性有所下降。分浸法制备的含Ｚｒ样品在９５０℃老化后活性最高。从γ－Ａｌ_２Ｏ_３缺陷尖晶石特征及高温脱结构水过程，探讨了助剂抑制α－Ａｌ_２Ｏ_３生成的原因。     

皮胶原纤维对单宁的选择性吸附

用动物皮为原料制备皮胶原纤维吸附材料, 研究了这种吸附材料对单宁的吸附特性. 结果表明, 皮胶原纤维对单宁具有非常好的吸附选择性和高吸附容量, 通过一次吸附, 单宁的去除率可达90%以上, 而其他有效成分损失率小于10%. 单宁在胶原纤维上的吸附属于氢键吸附; 其吸附平衡符合Freundlich方程; 其吸附动力学符合拟二级速度方程.     

CO2强化水洗对生物炭脱灰影响及作用机理研究

本实验提出一种先炭化后CO₂强化水洗的脱灰方法,选用甘蔗渣考察了生物炭的制备温度、CO₂强化水洗温度及时间对脱灰效果的影响。结果表明,炭化温度升高,脱灰率呈先增加后降低的趋势,而水洗温度升高和时间的延长则趋势相反,对于300℃甘蔗渣炭,经40℃水洗4 h脱灰率可达57%。与炭化前水洗脱灰相比,先炭化后脱灰使甘蔗渣热解炭的固定碳含量和炭收率分别提高7%和3%。分析认为,在脱灰过程中,CO₂通入水中扩散溶解形成碳酸,与部分盐反应形成溶于水的盐类,K、Na和Ca脱除率超过50%,部分方解石、白云石被脱除。该过程较单独水洗显示出较高的脱灰率和普适性,但是脱灰率与生物炭的灰分组成和类型相关,对花生壳、杨木热解炭脱灰率均超过30%。     

季铵盐插层蒙脱土及其去除海洋卡盾藻的研究

利用插层法制备了5种季铵盐改性的蒙脱土,通过FTIR、XRD和DTG等表征表明5种季铵盐已成功插入蒙脱土中;随后以中国典型赤潮藻海洋卡盾藻(Chattonella marina)为研究对象,考察了5种季铵盐改性蒙脱土的除藻效果。发现以双溴化十四烷基二甲基乙基溴化铵改性的蒙脱土在用量为8mg·L-1时,24h内对海洋卡盾藻的去除率最高,可达100%,而未改性蒙脱土在相同条件下除藻率仅为5.64%;除藻效果与除藻剂的结构有密切关系,在官能团相同时,链长数为14的脂肪族季铵盐除藻率最高,24h可达67.03%;在链长数相同时,含吡啶官能团的季铵盐比脂肪族季铵盐除藻率高,24h为33.62%,且随时间延长明显提高。渗溢性评估实验显示,改性蒙脱土经72h浸泡后表观插层率从71.9%降低到69.6%,表明除藻剂在水体中基本不释放。     

高纯碳研究：Ⅰ.含氟酸对煤和石墨的脱灰效果

以含氟酸为脱灰剂对煤和石墨提纯以制取高纯碳。考察了脱灰过程中酸浓度、脱灰温度和时间对脱灰效果的影响,提出了含氟酸脱灰制取高纯碳的最佳工艺路线。结果表明,含氟酸是良好的煤和石墨的脱灰剂,能有效地脱除煤和石墨中的各种矿物质组分。其中,HF酸对Si,Al,Fe组分有显著的脱除效果,H_2SiF_6酸对除Si以外的其它组分均有显著的脱除效果,特别是对Ca,Mg组分的脱除效果尤为突出。本文还通过对脱灰产品中矿物组分的组成分析,初步讨论了含氟酸脱灰过程机理。     

应用红外光谱研究脱灰对伊敏褐煤结构的影响

对伊敏褐煤的原煤和脱灰煤进行了红外光谱分析,并通过分段分峰拟合分析了脱灰前后伊敏煤结构的变化。结果表明,脱灰处理对煤中有机结构会产生一定影响。对脂氢和羟基氢键有机结构影响较小,脱灰后,脂氢结构中CH₂不对称伸缩振动没有变化,CH伸缩振动明显减少,而CH₂对称伸缩振动和CH₃不对称伸缩振动略有增加;羟基氢键结构中羟基N羟基、自缔合羟基氢键以及羟基π氢键的强度有所降低,而环氢键和羟基醚氢键的吸收强度有所增加;对芳香结构和含氧官能团的影响较大,芳香结构由原煤中的苯环三取代占主导地位转变为脱灰煤中的苯环三和四取代;含氧官能团中烷基醚和脂肪羧酸脱灰后吸收峰的强度明显减弱,这是由于水解反应导致的,而酚羟基和羧酸脱灰后吸收强度明显增强。     

高温煤气净化高效脱氯剂的研究

在固定床反应器中对四种高温煤气脱氯剂进行了筛选研究。在５５０℃温度下,所有被测试的脱氯剂都能迅速与ＨＣｌ气体发生反应,在反应开始的一段时间同都能使混合气体中的ＨＣｌ从０．１％降低到０．０００１％以下。在相同的反应条件下,ＣＮ１脱氯剂具有最高的穿透时间,穿透氯容量和饱和氯容量。在３００￣７００℃之间,温度越高,ＣＮ１脱氯剂吸收氯容量越高,反应性越好,在高空速下,脱氯剂脱氯效果明显下降。     

八面沸石用(NH4)2SiF6脱铝补硅的研究:Ⅳ.反应机理

在典型的(NH_4)_2SiF_6与(NH_4Na)Y反应条件下分别研究了(NH_4Na)Y与NH_4F、HCl和NH_4F+HCl以及HY与NH_4F的作用。发现F~-单独不能使(NH_4Na)Y脱骨架铝,HCl也不能使其脱铝(在NH_4Ac缓冲液中),而HCl+NH_4F可使其脱铝并保持较高的结晶度。据此认为(NH_4)_2SiF_6与沸石反应时,沸石的骨架铝是在H~+和F~-的共同作用下逐步脱出的,而不是被F~-抽取掉。根据反应机理提出脱铝沸石中有少量组分性氟存在,水洗不能将其除去。     

钙钛矿型稀土复合氧化物催化剂上一氧化碳的选择氧化

考察了在钙钛矿型稀土复合氧化物催化剂上，氢气中一氧化碳选择氧化的催化性能，发现该催化剂具有优良的催化活性和选择性。LaMnO3中的锰被铜部分取代后可以提高其催化活性，当其中的镧再被锶或钡部分取代后所得的催化剂的催化活性进一步提高。其中以La0.8Sr0.2Mn0.5Cu0.5O3的催化活性为最佳，在该催化剂上，在40 000 mL·g－1·h－1下，155 ℃时CO可被完全转化为CO2，此时的选择性达54%，与铂催化剂的性能相近。反应气中加入CO2时，CO转化率下降，但选择性有所提高；加入水蒸气则使CO的转化率和反应选择性均下降。     

Copolymerization of CO2 and cyclohexene oxide

Generation of high value polymers from carbon dioxide is of general technological interest given that CO2 is both inexpensive and relatively easy to handle on an industrial scale. Previous work on the use of CO2 as a comonomer has focused primarily on development of new catalysts, and the effects of conventional process variables such as temperature and concentration on the polymerization outcome have not been examined in great detail. Recently, we, as well as Darensbourg and colleagues, have shown that one can generate zinc-based catalysts for the polymerization of CO2 and cyclohexene oxide which produce over 400 grams of polymer per gram of metal. In this paper, we use a product of the reaction between zinc oxide and the fluorinated half-ester of maleic anhydride to generate copolymers of CO2 and cyclohexene oxide where CO2 is both reactant and sole solvent. In general, we found that the outcome of the polymerization depends greatly on the proximity to the ceiling temperature and the critical cyclohexene oxide concentration, and also on the phase behavior of the cyclohexene oxide-CO2 binary.     

Enhancing reaction rate of transesterification of glycerol monostearate and methanol by CO(2)

The effect of CO2 as a green additive on the reaction rate of transesterification of glycerol monostearate with methanol was studied at 333.15 and 343.15 K up to 10.5 MPa. It was demonstrated that addition of CO2 in the reaction system could increase the reaction rate significantly. The phase behavior of the CO2+methanol+ glycerol monostearate ternary system was also determined at 333.15 and 343.15 K. It is shown that addition of CO2 can enhance the miscibility of the reactant. The main reasons for the reaction rate enhancement are that CO2 can enhance the miscibility of the reactants, reduce the viscosity of the reaction mixture, and increase the diffusion coefficients of the reactants.     

Coadsorption of CO and O(2) on selected gold clusters: evidence for efficient room-temperature CO(2) generation

Spurred by the recent demonstrations of the size- and support-dependent reactivity of supported gold clusters, here we present results on the coadsorption of CO and O(2) on selected anionic gold clusters, Au(N)(-), in the gas phase. O(2) adsorbs in a binary (0,1) fashion as a one-electron acceptor on the Au(N)()(-) clusters, with even-N clusters showing varying reactivity toward O(2) adsorption, while odd-N clusters show no evidence of reactivity. CO shows a highly size-dependent reactivity for Au(N)(-) sizes from N = 4 to 19, but no adsorption on the gold dimer or trimer. When the gold clusters are exposed to both reactants, either simultaneously or sequentially, interesting effects have been observed. While the same rules pertaining to individual O(2) or CO adsorption continue to apply, the preadsorption of one reactant on a cluster may lead to the increased reactivity of the cluster to the other reactant. Thus, the adsorbates are not competing for bonding sites (competitive coadsorption), but, instead, aid in the adsorption of one another (cooperative coadsorption). New peaks also arise in the mass spectrum of Au(6)(-) under CO and O(2) coadsorption conditions, which can be attributed to the loss of a CO(2) molecule (or molecules). By studying the relative amount of reaction, and relating it to the reaction time, it is found that the gas-phase Au(6) anion is capable of oxidizing CO at a rate 100 times that reported for commercial or model gold catalysts.     

Comparative theoretical study of the dissociation process of the isoelectronic molecules BH3CO,CH2CO,HNCO, CO2 and BH3N2, CH2N2, HN3, N2O

Anab initio study of the electronic structure of several 22-electrons molecules is presented. The equilibrium geometries of their ground state are calculated at the SCF level using the 6–31G basis set and are found to be in good agreement with the experimental geometries. The dissociation process of these molecules leading to the isoelectronic products CO or N₂ on the one hand and BH₃, CH₂, NH and O on the other hand is studied. The least-energy dissociation paths of the ground states determined at the SCF level are compared on the basis of electron density interactions. The dissociation energies corresponding to the two lowest dissociation channels are calculated. In these calculations, the correlation energy is taken into account using a non-variational method developed previously. The calculated values of dissociation energies are in good agreement with the existing experimental values. The results permit to predict values for HNCO, BH₃CO and CH₂N₂ and to confirm the instability of BH₃N₂.Aspirant du Fonds National Belge de la Recherche Scientifique.     

Structure of Mn2(CO)10 and Mn2(CO)9: Insights from ab initio calculations

Optimization of the Mn–Mn distance in Mn₂(CO)₁₀ with various basis sets of at least doublezeta quality results in Mn–Mn bond lengths in the range of 3.07–3.15 Å, 0.2–0.25 Å longer than the experimental value of 2.895 Å. Incrementing the basis set with diffuse p functions (exponent 0.0332) on the carbon atoms improves the calculated bond length to a value of 2.876 Å at the CI level, as a consequence of a charge transfer between each Mn atom and the equatorial carbonyls of the other Mn atom. For Mn₂(CO)₉ four structures have been studied at the SCF and CI levels with assumed geometries. The structure with a symmetric bridging carbonyl turns to be much higher in energy at the SCF level. The two structures which are purely metal–metal bonded [corresponding to the departure of an axial or equatorial carbonyl from Mn₂(CO)₁₀] are nearly degenerate in energy and more stable than the structure with a semibridging carbonyl by 5 kcal/mol at the SCF level and 10–11 kcal/mol at the CI level (seemingly at variance with the conclusions of matrix experiments that favor the semibridging structure).     

Oxidation of Styrene with Molecular Oxygen in Supercritical CO2

The oxidation of styrene with molecular oxygen catalyzed by PdCl2 CuCl2 has been investigated in supercritical CO2 with a batch reactor. The oxidative system of styrene contains four components at the beginning and seven components during the reaction. The critical temperature, critical pressure, and critical density at different conversions are determined by using a high-pressure view cell. The effect of phase behavior on the conversion and selectivity were studied. Experimental results showed that the critical parameters of the reaction mixture at fixed initial molar ratio changed with the conversion of reactant. The conversion of styrene reached maximum near the critical density of the reaction mixture. Product selectivity also varied with density of reaction mixture and could be tuned to some degree.     

On the origin of satellite peaks in valence photoemission from CO ON Cu(110)

The valence-level photoelectron spectrum of CO absorbed on copper surfaces exhibits extra features in the region 10–20 eV below E_F which are attributed to multielectron excitations. We have recorded the satellite intensity as a function of photon energy in the system CO/Cu(110) using synchrotron radiation. It is found that the occurrence of all satellites, including some which are observed for the first time, can be explained in terms of the SCF Xα SW model calculations by Messmer et al.     

The Mutual Conversion of CO2 and CO in Dielectric Barrier Discharge (DBD)

Non-equilibrium plasma, which was engendered by dielectric barrier discharge (DBD) was used to analyze the mutual conversion between CO₂ and CO. The results showed that the conversion ratio of CO increased monotonously with the increasing voltage. But CO₂ was not so. Its conversion ratio reached maximum when the voltage was 3600 V in Ar system. It also showed that the existence of water molecules was more advanageous for the conversion of CO to CO₂ in Air system than in oxygen system, and the conversion ratio could reach 75.8% when the relative humidity was 100%. We also discussed the energy yield and energy efficiency, and the result was that high voltage and high concentration of reactant was disadvantageous for energy utilization.     

CO oxidation over supported Pt clusters at different CO coverage

CO adsorption and oxidation over supported Pt₁₄ with different CO coverage on TiO₂(110) surface were investigated using density functional theory (DFT) calculations and thermodynamic analysis. According to the phase diagram, Pt₁₄/TiO₂(110) and 11CO@Pt₁₄/TiO₂(110) were chosen to represent the low and high CO coverage of Pt clusters, respectively. Our study shows that the high coverage of CO can induce the structural change of supported Pt clusters and weaken the interaction between Pt clusters and TiO₂ support. The CO adsorption and oxidation mechanism depends on the CO coverage, which is determined by the experimental reactant composition, pressure, and temperature. At low CO coverage, the dissociated oxygen is active specie to form CO₂ by reacting with CO. At high coverage, the molecular oxygen can directly react with CO via the formation of OOCO intermediate. Our proposed mechanisms provide useful information for understanding the CO oxidation over Pt clusters with different CO coverage. © 2016 Wiley Periodicals, Inc.