黄连木籽油制备生物柴油固体碱催化剂研究

采用新型固体碱Li2O/MgO替代传统的均相碱催化剂,催化黄连木籽油与甲醇进行酯交换反应制备生物柴油。考察了载体类型、浸渍液中Li元素浓度、焙烧温度和焙烧时间等制备条件对催化活性的影响,确定了最佳制备条件。结果表明:优化制备的Li2O/MgO固体碱催化剂,在浸渍液中Li元素质量分数为3%,焙烧温度600℃,焙烧时间6 h,用于酯交换反应时具有良好的催化活性,在反应温度65℃,醇油物质的量比9:1,固体碱催化剂用量为油质量的2%,反应3 h产物中棉籽油甲酯含量达到98%,反应10次甲酯含量维持在90%左右,其指标基本达到美国的ASTM标准和德国的DINE标准。     

油脂醇解固体碱催化剂的制备及表征

以硝酸钙、硝酸锌、乙酸镁、乙酸铝为原料,碳酸钠为沉淀剂进行共沉淀反应,先制得钙、镁、锌碳酸盐及氢氧化铝混合沉淀,再经陈化、水洗、干燥、焙烧制得钙镁锌铝固体碱催化剂。将蓖麻油甲醇解反应中的蓖麻油转化率作为活性评价指标,采用正交试验考察了制备条件对催化剂活性的影响,得到制备催化剂的优化条件为:n(Ca)∶n(Mg)∶n(Zn)∶n(Al)=2∶0.5∶0.5∶1,混合溶液p H 8,焙烧温度850℃,焙烧时间7 h。将优化条件下制备的固体碱催化剂用于催化蓖麻油甲醇解反应,蓖麻油转化率达93.2%。采用热重分析、X射线衍射、N2吸附-脱附、扫描电镜及Hammett指示剂滴定法对催化剂及其前驱体进行了表征。结果显示:催化剂前驱体在700~800℃温区有1个明显的失重台阶,在800℃以后质量基本不随温度变化;固体碱催化剂主要由Ca O、Zn O及Mg O3种晶体构成,其比表面积为44.08 m~2/g、孔容为0.062 65 cm~3/g,特征为多孔连续型蜂窝状结构;固体碱催化剂的碱强度在7.2~15.0之间,总碱位量为14.895 mmol/g。     

KF-MgO固体碱催化剂的表征及油脂醇解活性

以二水合氟化钾、乙酸镁(四水)为原料,经过混合研磨、焙烧制得KF-MgO固体碱催化剂。采用单因素实验得到的优化制备条件为：摩尔比n(KF·2H₂O):n(MgAc₂·4H₂O)=1,焙烧温度500℃,焙烧时间3 h。将制得的固体碱催化剂催化蓖麻油与甲醇的酯交换反应,得生物柴油的折射率为1.462 6,蓖麻油转化率为96.36%。通过热重分析、X射线衍射和扫描电镜对最佳条件下制备的KF-MgO固体碱催化剂及其前驱体进行表征,结果表明,KF-MgO固体碱催化剂的前驱体在500℃左右分解过程基本结束。催化剂主要以KMgF₃的形式存在,呈蜂窝状,有一定数量的孔洞。     

CaO/Co-Al-O固体碱的制备、表征及其油脂醇解活性

采用共沉淀、浸渍及高温焙烧的方法制备了Ca O/Co-Al-O固体碱催化剂。采用正交实验考察了制备条件对Ca O/Co-Al-O固体碱油脂醇解活性的影响,得到固体碱催化剂的优化制备条件为:Co与Al摩尔比3∶1、顺加法、Ca(Ac)2浸渍液质量分数0.25、焙烧温度700℃、焙烧时间6 h。以优化条件下制备的Ca O/Co-Al-O固体碱为催化剂,在甲醇与蓖麻油摩尔比9∶1、催化剂与蓖麻油质量比0.04∶1、搅拌速率400 r/min、反应温度65℃、反应时间3 h的条件下,蓖麻油转化率为94.74%。采用TG-DTA、FT-IR、BET及XRD技术对固体碱催化剂及其前驱体进行了表征。结果显示:固体碱催化剂前驱体Ca(Ac)2/Co-Al水滑石TG曲线有3个失重台阶,分别出现在100~200℃、200~300℃及680~730℃;Ca O/Co-Al-O固体碱催化剂的BET比表面积为42.7 m2/g,BJH脱附累积孔容为0.29 cm3/g,BJH脱附平均孔半径为11.4 nm;Ca O/Co-Al-O固体碱中的活性组分Ca O以无定形或微晶的形式高度分散于Co Al2O4及Co3O4表面。     

固体碱催化黄连木籽油制备生物柴油

以黄连木籽油为原料,研制出适用于其与甲醇发生酯交换反应制备生物柴油的固体碱催化剂。考察了浸渍液中Li元素浓度、焙烧温度和焙烧时间等制备条件对催化活性的影响,确定了最佳制备条件。结果表明,优化制备的Li2O/CaO固体碱催化剂,在浸渍液中Li元素质量浓度为4%,焙烧温度700℃,焙烧时间5h,用于酯交换反应时具有良好的催化活性,在反应温度60℃,醇油摩尔比12∶1,固体碱催化剂用量为油质量的1.2%,反应3h产物中黄连木籽油甲酯含量达到97%,制备得到的生物柴油质量达到国家柴油机燃料调合用生物柴油（BD100）标准。     

La/CaO/MgO/Al_2O_3固体碱催化剂的制备及表征

以镧、钙、镁、铝的硝酸盐为原料,以尿素为沉淀剂,采用均匀沉淀及高温焙烧的方法制备了La/Ca O/Mg O/Al2O3固体碱催化剂。采用单因素实验考察了制备条件对催化剂活性的影响,得到制备固体碱催化剂的优化工艺条件为:n(La)∶n(Ca)∶n(Mg)∶n(Al)=0.027 0∶4∶2∶2,反应温度120℃,焙烧温度750℃,焙烧时间8 h。将优化条件下制备的La/Ca O/Mg O/Al2O3固体碱用于催化蓖麻油和甲醇的酯交换反应,在n(醇)∶n(油)=9∶1、m(催化剂)∶m(油)=0.04∶1、搅拌速率550r/min、反应温度65℃、反应时间3 h的条件下,蓖麻油转化率可达88.44%。采用Hammett指示剂法、TG、BET、XRD及SEM对催化剂及其前驱体进行了表征。结果表明:La/CaO/MgO/Al_2O_3固体碱的碱强度为7.2~11.2;当温度超过830℃时,La-Ca-Mg-Al水滑石的质量几乎不再随温度变化;催化剂比表面积为50.84 m2/g、孔容为0.107 3 cm3/g,催化剂主要由Ca O、Mg O及Al2O33种晶体组成。     

钙镁铝固体碱催化剂的制备及表征

采用氢氧化钠、硝酸钙、硝酸镁制得钙镁氢氧化物沉淀,采用氨水、乙酸铝制得氢氧化铝沉淀。两种沉淀依次经陈化、抽滤、洗涤、干燥后,混合焙烧即得钙镁铝固体碱催化剂。以蓖麻油甲醇醇解反应为模型反应,蓖麻油转化率为活性评价指标,采用正交实验考察了催化剂制备条件对其催化活性的影响;采用Hammett指示剂滴定法、TG、XRD、BET及SEM技术对催化剂及其前驱体进行了表征。结果表明:制备催化剂的优化条件为n(Ca)∶n(Mg)∶n(Al)=1.5∶1.5∶1、陈化时间18 h、焙烧温度400℃、焙烧时间6 h,对应的蓖麻油转化率平均可达88.3%,且其催化活性较稳定;催化剂前驱体在300400℃有1个明显的失重台阶,在800℃以后质量基本不随温度变化;钙镁铝固体碱催化剂的碱强度在7.2~15.0之间,总碱位量为12.262 mmol/g,主要由CaO、MgO两种晶体构成,其比表面积为83.83 m2/g、孔容为0.173 2 cm3/g,其颗粒大小在2~20μm之间。     

固体碱KF/CeO2催化大豆油制备生物柴油的研究

以硝酸铈铵为铈源，采用水热法制备CeO₂载体，浸渍法制备KF/CeO₂固体碱催化剂，并采用X射线衍射(XRD)、扫描电镜(SEM)和比表面积(BET)对催化剂进行表征。结果表明：KF/CeO₂固体碱对大豆油制备生物柴油有催化作用；催化剂的最佳制备条件为KF负载量40%、焙烧温度500℃、焙烧时间3 h;制备生物柴油的最佳反应条件为催化剂用量为大豆油质量的3.0%、醇油摩尔比9∶1,在该条件下生物柴油的最高产率为86.7%。     

CaO/(Mg-Fe-O)固体碱的制备及其酯交换催化活性研究

采用共沉淀、浸渍及高温焙烧的方法制备了Ca O/(Mg-Fe-O)固体碱催化剂,以蓖麻油转化率为催化剂活性评价指标,采用正交实验考察了制备条件对催化剂酯交换催化活性的影响。得到的优化条件为:Mg/Fe摩尔比3∶1,Ca(Ac)2浸渍液质量分数15%,浸渍时间12 h,焙烧温度800℃,焙烧时间2 h。以优化条件下制备的Ca O/(Mg-Fe-O)固体碱为催化剂,用于蓖麻油和甲醇酯交换反应,蓖麻油转化率可达94.74%。采用TG-DTA、FTIR、BET及XRD技术对催化剂及其前驱体进行了表征。结果表明:当温度超过750℃时,Ca(Ac)2/(Mg-Fe水滑石)几乎不再失重;Ca O/(Mg-Fe-O)固体碱和Ca(Ac)2/(Mg-Fe水滑石)相比,其—OH和CO2-3的红外吸收峰显著下降;负载于Ca O/(Mg-Fe-O)固体碱催化剂介孔中的Ca O起主要催化作用;Ca O/(Mg-Fe-O)固体碱中的Ca O以无定形或微晶的形式高度分散于Mg Fe2O4及Mg O表面。     

钙基固体碱催化剂用于花生油酯交换制备生物柴油

将钙基固体碱催化剂CaO和CaO/MgO用于催化花生油与甲醇酯交换制备生物柴油,考察了催化剂的制备条件,优化了CaO和CaO/MgO催化花生油酯交换反应工艺.研究表明,利用廉价碳酸钙作为原料,在800～900℃下N2气氛中煅烧制备的CaO具有比较好的催化活性;而CaO/MgO催化剂比较适宜的制备条件是用22.6%的Ca(Ac)2溶液浸渍MgO载体1次,在600℃下煅烧.CaO/MgO在空气中存放易失去活性,需在800～900℃下N2气氛活化.CaO和CaO/MgO催化剂均可使花生油与甲醇的酯交换反应在醇油摩尔比12:1、催化剂用量2%、反应温度65℃、反应时间2 h的条件下获得80%以上的酯交换转化率.与CaO相比,CaO/Mgo催化剂具有较高的抗水性和抗酸性,以及较好的重复使用性.     

负载型固体碱催化制备生物柴油重复性能比较

采用共沉淀、浸渍及焙烧的方法制备了Ca O/Mg-Al-O及Ca O/Zn-Al-O固体碱催化剂;采用共沉淀、焙烧及研磨的方法制备了KF/Mg-Al-O及KF/Ca-Al-O固体碱催化剂。采用醇洗、干燥及焙烧的方法对使用过的催化剂进行活化处理后用于下一次实验。以蓖麻油和甲醇的酯交换反应为活性评价反应,考察了催化剂重复使用次数对催化剂活性的影响。应用Hammett指示剂滴定法、XRD技术对新催化剂及使用后经活化处理的催化剂进行了表征,并对催化过程中碱溶解流失和析出的甘油量、总甘油量进行了测定。结果表明:Ca O/Mg-Al-O、Ca O/Zn-Al-O、KF/Mg-Al-O和KF/Ca-Al-O固体碱催化剂第一次使用催化活性很好,第二次使用催化活性较差;新催化剂的碱量均比使用过的催化剂的碱量高得多;新催化剂的晶体结构和使用过的催化剂的晶体结构差别很小;新催化剂的碱溶解流失均比较大,且生成的甘油量均较多。     

Catalyzed destructive adsorption of environmental toxins with nanocrystalline metal oxides. Fluoro-, chloro-, bromocarbons, sulfur, and organophosophorus compounds

In the temperature range of 300-500 degrees C, solid nanocrystalline oxides react nearly stoichiometrically with numerous halocarbons, sulfur, and organophosphorus compounds. In some cases, the reaction efficiencies can be improved by the presence of a small amount of transition-metal oxide as catalyst; for example, Fe2O3 on CaO and mobile intermediate species such as FeCl3 or Fe(SO3)x are important in the catalytic process. Herein, a series of environmentally problematic compounds are discussed, including CCl4, COS, CS2, C2Cl4, CHCl3, CH2Cl2, CH3Cl, and (CH3O)2P(O)CH3. Nanocrystals of CaO coated with a thin layer of Fe2O3 (or other transition metals) =[Fe2O3]CaO, or intimately mixed =Fe2O3/CaO were compared with pure CaO. It was found that (a) the presence of a small amount of surface [Fe2O3] or other transition-metal oxide can have a marked effect on the destructive adsorption activity, (b) for some reagents, such as CCl4, C2Cl4, SO2 and others, the nanocrystalline CaO can react in stoichiometric amounts, especially if a transition-metal oxide catalyst is present, (c) although the reaction with dimethylmethylphosphonate is surface-limited, the nanocrystalline calcium oxide performed well and in high capacity, (d) nanocrystalline calcium oxide exhibits near stoichiometric activitywith several interesting sulfur-containing compounds, such as COS and CS2, (e) unfortunately, most fluorocarbons were not destructively adsorbed at 500 degrees C under the conditions employed; however, some of these can be effectively mineralized over the calcium oxide at higher temperatures. These compounds include C2F6, C3F6, C2ClF3, and CHF3, and (f) upon reaction, surface areas decreased considerably, from about 100 to about 10 m2/g. The results of these experiments further demonstrate that, with the proper choice of catalytic material, some solid-gas reactions can be engineered to be rapid and essentially stoichiometric.     

Optimization of chemical activation of cotton fabrics for activated carbon fabrics production using response surface methodology

Abstract

The preparation of activated carbon fabric (ACF) from cotton fabric treated with phosphoric acid (H₃PO₄) was optimized using the response surface methodology (RSM). Experimental activation variables including; impregnation ratio, heating rate, activation temperature, and activation time were optimized based on the responses evaluated (adsorption capacity, yield of the produced ACF). The operation conditions for obtaining the ACFs with the highest the adsorption capacity and process yield were proposed. Optimized conditions were: impregnation ratio of 2, heating rate of 7.5 °C min^?1, the activation temperature of 500 °C, and the activation time of 30 min. The ACFs produced under optimized conditions were characterized by scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDX). The surface area and pore volume of carbon nanostructures were characterized by nitrogen adsorption isotherm at 77 °K using BET method. The obtained results showed that the produced ACFs have developed porous structure, fabric shape, BET surface area (690 m²/g) and total pore volume (0.3216 cm³/g), and well-preserved fibers integrity.     

Al_2O_3无机膜的制备及表面自由能计算

以异丙醇铝(AIP)为前驱体,采用溶胶-凝胶法制备Al_2O_3无机膜,并对不同温度焙烧的Al_2O_3无机膜进行接触角测试及表面自由能计算.结果表明,蒸馏水在膜材料表面接触角均小于90°,膜材料表现为亲水特性;随着焙烧温度的升高,Al_2O_3无机膜的表面自由能先减小后增大,当焙烧温度为350℃时,表面润湿性最弱,表面自由能达到最小值54.95×10~(-5)N·cm~(-1),其色散、偶极矩以及氢键分量分别为26.53×10~(-5),14.62×10~(-5)和13.80×10~(-5)N·cm~(-1).     

Uptake of fluoride by tea plant (Camellia sinensis L) and the impact of aluminium

Tea plant (Camellia sinensis L) accumulates large amounts of fluoride in mature leaves from soils of normal fluoride availabilities, but the properties of fluoride absorption by this plant species are not well understood. The present study examined the characteristic of fluoride uptake by tea plants and the impact of Al with solution and soil experiments. The results showed that the fluoride taken up by tea plants was largely and readily transported, in particular to the leaves. The fluoride in leaves increased linearly with fluoride concentrations in the uptake solution (R² = 0.75, P < 0.001) or in the soil (R² = 0.88, P < 0.001), whereas those in root and stem were only marginally influenced. Including Al in solution or adding Al to the soil apparently increased the uptake and translocation of fluoride to the leaves. The concentrations of fluoride in the leaves were significantly (P < 0.05) increased by 19.1% or 37.7% when 18.5 µmol l^?1 Al or 74.1 µmol l^?1 Al respectively was included in the uptake solution, compared with the control without Al during an uptake period of 22 h. Similarly, Al application (100 mg kg^?1) to soil led to significantly higher fluoride concentrations in mature leaves and new shoots (one bud with three leaves). By contrast, the concentrations of Al in leaves in solution and soil experiments were not affected by fluoride and Al treatments. Nevertheless, higher Al concentrations after Al and fluoride additions were observed in the new shoots in soil experiments. Copyright © 2003 Society of Chemical Industry     

赤泥为原料制备除氟剂的实验研究

赤泥是一种具有污染性且产量巨大的废弃物,实验以广西平果铝厂的拜耳法赤泥为主要原料,加入一定量的添加剂Na_2SiO_3·9H_2O、CaO、碳粉等,将赤泥制成球状并进行焙烧处理.采用XRD分析方法对所得样品进行物相分析,研究了赤泥除氟剂的吸附时间、焙烧温度、焙烧时间、溶液pH值对除氟性能的影响.结果表明：采用焙烧温度700℃、焙烧时间1h条件下活化的赤泥除氟剂,溶液中氟离子的浓度可从19 mg/L下降到0.37 mg/L,吸附容量达到0.47 mg/g,氟去除率达98％,同时受制备条件及pH值的影响很大.     

钙矾二元复合金属氧化物催化大豆油酯交换研究

实验制备CaO/V2O5固体碱催化剂,研究钙钒摩尔比和煅烧温度对催化剂活性影响;结果表明,最适制备催化剂条件为:钙矾摩尔比3∶1、煅烧温度823 K。考察该催化剂对油脂酯交换反应活性,CaO/V2O5催化大豆油酯交换最适反应条件为:醇油摩尔比15∶1、催化剂用量6.2 wt.%、反应时间4 h,大豆油转化率达80%;该催化剂重复使用5次后,活性并没明显降低,游离脂肪酸和水分含量对该催化剂活性影响很小。     

制备条件对Ni／Al2O3催化剂催化性能的影响

用混合杂多酸处理工业ｒ－Ａｌ２Ｏ３载体，制备了一种低镍含量Ｎｉ／Ａｌ２Ｏ３催化剂。经微反等证实；此催化剂在苯加氢制环己烷反应中所表现出的催化性能均与催化剂的制备条件密切相关。     

氧化钙、氧化镁协同氧化铝留硅蒸煮工艺研究

针对麦草浆黑液中SiO2引起的＂硅干扰＂问题,对氧化钙、氧化镁协同氧化铝留硅的烧碱-蒽醌法制浆工艺进行了研究。结果表明：当氧化铝∶氧化镁∶氧化钙为0.5∶0.5∶2时留硅作用最明显,成本最低。相应工艺条件为：用碱量14%,蒽醌0.05%,氧化铝用量0.5%,氧化镁用量0.5%,氧化钙用量2%,液比1∶5,温度160℃,保温30min。在此工艺条件下,纸浆的灰分含量增加了2.54%,SiO2含量增加了1.39%。     

Better lime purification of sugar beet juice obtained by low temperature aqueous extraction assisted by pulsed electric field

Purification of the sugar beet juices obtained by novel low temperature extraction (at 30 °C) assisted by pulsed electric field (PEF) and conventional high temperature extraction (at 70 °C) was done by the method of lime-carbon dioxide treatment. The total concentration of lime used for the purification was varied from 6 to 15 kg of CaO/m³ of the juice. Filtration properties of the juices of first carbonation, as well as purity and coloration of the final thin juices, were compared. It was observed that purification of the juice extracted at 30 °C results in faster filtration of the juice of first carbonation and lower coloration of the final thin juice as compared to the juice obtained by means of purification of the juice extracted at 70 °C. It suggests that the quantity of CaO required for the efficient juice purification may be decreased from 15 kg/m³ (for the juice extracted at 70 °C without PEF treatment) to approx. 8 kg/m³ (for the juice obtained by PEF-assisted extraction at 30 °C).