微波辅助磺化稻壳灰催化合成苯并噻唑的研究

以绿色环保的稻壳灰为吸附剂负载氯磺酸制得固体酸催化剂,微波辅助下通过邻氨基苯硫酚和醛分子间的缩合反应"一锅法"制备得到2-取代苯并噻唑类化合物3a~3l,其结构经IR、1 H NMR和元素分析等测试技术加以确证;实验结果表明,酸预处理的稻壳高温煅烧后的稻壳灰能够有效负载经氯磺酸,在催化剂用量为8mol%,800 W功率下微波辐射反应5~15min,可制得到2-取代苯并噻唑目标化合物,合成收率为80%~95%,且该催化剂易于回收并反复使用。     

微波辅助下固体酸催化剂对稻壳热解油的催化加氢

微波辅助下,以甲醇为溶剂的固体酸催化剂对稻壳热解油的催化加氢,采用Gc/MS分析稻壳热解油催化前后正己烷萃取物.结果表明:稻壳生物油中的化合物十分复杂,主要成分为酮、酚、醛、酸和酯等含氧化合物;在固体酸催化下,酮和酚的含量大大降低;同时,稻壳热解油催化后正己烷的萃取物中的化合物种类也有所增加;微波辅助下,固体酸催化剂对...     

稻壳灰的制备及其对地聚物力学性能的影响

以稻壳为原料,研究稻壳在不同酸预处理条件和不同煅烧条件下制备得到的稻壳灰在表观性能、元素成分、反应活性、物相结构和微观结构等方面的特性差异及其对偏高岭土基地聚物力学性能的影响,确定稻壳灰最佳制备条件。结果表明,盐酸预处理会显著提高稻壳灰中无定形SiO₂的纯度,高达98.354%(质量分数)。经酸预处理的稻壳在550 ℃下煅烧60 min即可煅烧完全,稻壳灰反应活性最高。酸处理后的稻壳灰使地聚物的孔隙结构更加致密,550 ℃稻壳灰地聚物(10%(质量分数)稻壳灰+90%(质量分数)偏高岭土)28 d抗压强度最高,达53.3 MPa。通过综合影响分析,得到稻壳灰的最佳制备条件为:经2.5%(质量分数)盐酸溶液浸泡1 h后,550 ℃煅烧1 h。     

微波循环辐射辅助制备生物柴油反应器及工艺的研究

用鲜红薯为原料制备碳基固体酸催化剂,甲醇和地沟油为原料的混合液经自制的微波辐射反应器后,可以提高反应速率。对反应条件进行单因素和多因素分析,得出最佳反应条件。微波辅助催化地沟油制备生物柴油反应器可以提高反应速率,其最佳工艺条件:甲醇与地沟油摩尔比9∶1、微波功率密度1.5W/m L、微波辐射时间30 min、反应温度为60℃、催化剂质量分数3.5%。     

微波辅助ZrO2-SO2-4/SBA-15催化合成棕榈酸甲酯

以三嵌段醚共聚物P123作为模板剂、正硅酸乙酯为硅源,合成介孔分子筛SBA-15。以SBA-15为载体,利用尿素水解法制备ZrO₂-SO^2-₄改性的固体酸催化剂,对其进行表征。实验结果表明,合成的固体酸催化剂具有典型的介孔结构特征。将催化剂应用于微波法催化合成棕榈酸甲酯,考察反应时间、反应温度、辐射功率、酸醇物质的量比和催化剂用量对酯化率的影响,结果表明,在n（十六酸）∶n（甲醇）=1∶15、SZ/SBA-15催化剂用量0.8 g、反应时间20 min、反应温度40 ℃和微波辐射功率400 W条件下,酯化率可达87.70%,微波反应时间较传统合成方法大大缩短。     

微波辐射蒙脱土固定AlCl3催化合成乙酸异戊酯

以乙酸和异戊醇为原料,微波固相法制备的蒙脱土固定AlCl3固体酸为催化剂,合成乙酸异戊酯。实验表明:在催化剂用量为总反应物质量的8.5%、酸醇物质的量比为1∶2.5,微波功率为700 W,反应时间为10 min的条件下,酯化率达92.9%以上。催化剂重复使用5次仍具有较高的催化活性。     

微波辅助ZrO2-SO42-/SBA-15催化合成棕榈酸甲酯

以三嵌段醚共聚物P123作为模板剂、正硅酸乙酯为硅源,合成介孔分子筛SBA-15.以SBA-15为载体,利用尿素水解法制备ZrO2-SO42-改性的固体酸催化剂,对其进行表征.实验结果表明,合成的固体酸催化剂具有典型的介孔结构特征.将催化剂应用于微波法催化合成棕榈酸甲酯,考察反应时间、反应温度、辐射功率、酸醇物质的量比和催化剂用量对酯化率的影响,结果表明,在n(十六酸)∶n(甲醇)=1∶15、SZ/SBA-15催化剂用量0.8g、反应时间20min、反应温度40℃和微波辐射功率400W条件下,酯化率可达87.70％,微波反应时间较传统合成方法大大缩短.     

微波促进生物柴油制备的研究进展

以微波为促进手段进行生物柴油制备近几年受到广泛关注,本文从均相和非均相催化转酯化反应的角度,综述了微波促进生物柴油制备的国内外研究进展。与非均相催化过程相比,均相催化过程的研究更加广泛。均相催化剂的研究多以碱性催化剂为主,其反应速率快,但是副反应多。非均相催化剂的研究中,均有采用固体酸或者固体碱催化剂的报道,其中以活性炭为载体的固体催化剂具有廉价、高效的特点,但是其催化剂寿命需要进一步提高。     

微波促进下新型碳基固体酸催化合成草酸酯

在微波辐射条件下,以新型碳基固体酸为催化剂催化草酸分别与正丁醇、异丁醇、正戊醇、异戊醇的酯化反应。系统研究了微波功率、酸醇摩尔比、催化剂用量、反应时间等诸因素对酯化率的影响。实验结果表明：微波功率为500 W,在n（醇）/n（酸）=4.0︰1,催化剂用量占反应物料总质量的2.3%,反应时间为12 min条件下,不同草酸酯的酯化率均在95%以上。该固体酸重复使用多次,其催化活性基本不变。     

微波辐射蒙脱土固定三氯化铝催化合成草酸二丁酯

采用微波辐射技术,制备蒙脱土固定AlCl3固体酸催化剂。在密封灌内,通过微波辐射方法,用草酸与正丁醇为原料合成草酸二丁酯。研究结果表明,蒙脱土固定AlCl3固体酸催化剂具有良好的催化活性,当草酸用量0.02 mol,醇酸摩尔比为3.5∶1,催化剂用量为0.08 g,微波输出功率700 W,辐射时间11 min时反应的酯化率可达84.2%。     

变温处理稻壳灰脱除0价汞的实验研究

文章试图通过改变稻壳的变温处理时间及温度,观察不同处理条件下的稻壳灰吸附烟气中0价汞的能力,通过实验发现600-800℃下处理得到的稻壳灰吸附效果最好,最好的脱汞效率可达95%以上.低温下处理时间较短的稻壳灰对烟气中0价汞的吸附效果好,在今后的工业应用上值得进一步进行研究.     

Sulfonated rice husk ash (RHA-SO3H): A highly powerful and efficient solid acid catalyst for the chemoselective preparation and deprotection of 1,1-diacetates

Rice husk ash (RHA), as a source of amorphous silica, was treated with chlorosulfonic acid and sulfonated rice husk ash (RHA-SO₃H) as a highly powerful solid acid catalyst was obtained and characterized with a variety of techniques including IR, TGA, SEM, XRD, pH analysis, Hammett acidity function and BET method. This solid acid showed excellent catalytic activity for the protection and deprotection of aldehydes with Ac₂O at room temperature under solvent free conditions. The procedure gave the products in excellent yields in very short reaction times and good to high yields. Also this catalyst can be reused for several times without loss of its catalytic activity.     

具有高比表面积的稻壳灰的制备及其化学活性的研究

Preparation of rice husk ash with high specific surface area and chemical reactivity of the product are reported in this paper. The amorphous rice husk ash with high specific surface area of 311 m^2.g^-1 was produced by heating acid treated rice husk at 700~C for 4 h. The isotherms of rice husk ash are similar in shape to type Ⅱ of Brunaner‘s classification with mesopores being predominant. The rice husk ash has a high chemical reactivity, especially that pretreated with acid. This chemical reactivity depends on ashing temperature and pretreatment conditions. There is an exponential relation between the specific surface area of rice husk ash and the change in the conductivity of saturated Ca(OH)2 solution with rice husk ash, from which the specific surface area can be known according to the conductivity change.     

Potential aspect of rice husk biomass in Australia for nanocrystalline cellulose production

Nanocrystalline cellulose(NCC) was produced from rice husk biomass(Oryza sativa) by a chemical extraction process to explore the potential aspect of agro-waste biomass in Australia. In this work, the delignified rice husk pulp(D-RHP) was produced by alkaline delignification of raw rice husk biomass(R-RHB) using 4 mol·L~(-1) alkali solutions(Na OH) in a jacketed glass reactor under specific experimental conditions. D-RHP was bleached using 15% sodium hypochlorite, and the bleached rice husk pulp was coded as B-RHP. Finally,raw suspension of NCC was produced by the acid hydrolysis of B-RHP using 4 mol·L~(-1) sulphuric acid. The raw suspension of NCC was neutralized by a buffer solution and analyzed by TAPPI, FT-IR, XRD, SEM, AFM, and TEM. FT-IR spectra of NCC are different to R-RHB but similar with B-RHP and D-RHP. From XRD results, the crystallinity of NCC was found to be approximately 65%. In AFM analysis particle thicknesses have been confirmed to be in the range of(25 ± 15.14) nm or(27 ± 15.14) nm which is almost the same. From TEM analysis particle dimensions have been confirmed to be in the range of(50 ± 29.38) nm width and(550 ± 302.75) nm length with the aspect ratio ~ 11:1(length/diameter) at a 500 nm scale bar. On the other hand, at a 200 nm scale bar the particle dimensions have been confirmed to be in the range of(35 ± 17) nm width and(275 ± 151.38)nm length with the aspect ratio ~ 8:1. The aspect ratio of individual crystalline domain was determined in TEM analysis which is 10:1(100/10). Therefore the aspect ratios and dimensions of nanoparticles in NCC suspension are almost the same and in nano-meter scale, as confirmed from both AFM and TEM results. The yield of NCC from B-RHP was found to be approximately 95%, and the recovery of cellulose from R-RHB is about 90%.     

Study on the pozzolanic properties of rice husk ash by hydrochloric acid pretreatment

The pozzolanic properties of rice husk ash by hydrochloric acid pretreatment are reported in the paper. Three methods have been used to estimate the pozzolanic activity of rice husk ash. The heat evolution and the hydration heat of cement, the Ca(OH)₂ content in the mortar and the pore size distribution of mortar are determined. It is shown that compare with the rice husk ash heated untreated rice husk, the sensitivity of pozzolanic activity of the rice husk ash heated hydrochloric acid pretreatment rice husk to burning conditions is reduced. The pozzolanic activity of rice husk ash by pretreatment is not only stabilized but also enhanced obviously. The kinetics of reaction of rice husk ash with lime is consistent with diffusion control and can be represented by the Jander diffusion equation. A significant increase in the strength of the rice husk ash (pretreated) specimen is observed. The results of heat evolution indicate that the rice husk ash by pretreatment shows the behavior in the increase of hydration of cement. The cement mortar added with the rice husk ash by pretreatment has lower Ca(OH)₂ content after 7 days and the pore size distribution of the mortar with the rice husk ash with pretreatment shows a tendency to shift towards the smaller pore size.     

Effect of rice husk ash addition on CO2 capture behavior of calcium-based sorbent during calcium looping cycle

Rice husk ash/CaO was proposed as a CO₂ sorbent which was prepared by rice husk ash and CaO hydration together. The CO₂ capture behavior of rice husk ash/CaO sorbent was investigated in a twin fixed bed reactor system, and its apparent morphology, pore structure characteristics and phase variation during cyclic carbonation/calcination reactions were examined by SEM-EDX, N₂ adsorption and XRD, respectively. The optimum preparation conditions for rice husk ash/CaO sorbent are hydration temperature of 75 °C, hydration time of 8 h, and mole ratio of SiO₂ in rice husk ash to CaO of 1.0. The cyclic carbonation performances of rice husk ash/CaO at these preparation conditions were compared with those of hydrated CaO and original CaO. The temperature at 660 °C–710 °C is beneficial to CO₂ absorption of rice husk ash/CaO, and it exhibits higher carbonation conversions than hydrated CaO and original CaO during multiple cycles at the same reaction conditions. Rice husk ash/CaO possesses better anti-sintering behavior than the other sorbents. Rice husk ash exhibits better effect on improving cyclic carbonation conversion of CaO than pure SiO₂ and diatomite. Rice husk ash/CaO maintains higher surface area and more abundant pores after calcination during the multiple cycles; however, the other sorbents show a sharp decay at the same reaction conditions. Ca₂SiO₄ found by XRD detection after calcination of rice husk ash/CaO is possibly a key factor in determining the cyclic CO₂ capture behavior of rice husk ash/CaO.     

稻壳灰建材资源化的研究进展

稻壳灰是工业中稻壳作为生物燃料煅烧后的残留废弃物,利用稻壳灰生产建筑材料是其资源化的有效途径;简单介绍了稻壳灰的组成和烧制工艺,重点介绍了稻壳灰建材资源化的研究进展,尤其是稻壳灰在水泥、混凝土中的最新研究成果,以及稻壳灰在砂浆、砌块和保温建材中的应用;指出了稻壳灰建材资源化中存在的问题,需要进一步探索研究来更好的利用稻壳灰资源。     

Pastes of tricalcium silicate with rice husk ash

Pastes of tricalcium silicate with rice husk ash (RHA) were cured at 25°C for 1–245 days and examined by XRD, analytical electron microscopy, TG, acid extractions to determine unreacted rice husk ash, and trimethylsilylation. The rice husk ash was highly reactive, and contents of calcium hydroxide, referred to the ignited weight, never exceeded 3%. Initially, a product having a Ca/Si atom ratio of 0.1–0.2 was formed, but this was later replaced by one having a Ca/Si ratio of approximately 1.3. The proportion of the Si in the hydration products that was present as polymeric ions was greater than that found in pure C₃S or C₃S-fly ash pastes of similar age, but the anion size distributions within the polymer were all broadly similar.     

Hydrothermal conversion of rice husk ash to faujasite-types and NaA-type of zeolites

The faujasite-type of zeolites (NaX and NaY) and NaA-type of zeolite were synthesized from rice husk ash (RHA) via the hydrothermal conditions. The combustion of rice husk at controlled temperature of 600 °C for an hour in open air produce more than 90% of amorphous silica in the ash which was reactive towards the synthesis of zeolites. The formation of zeolite NaY from RHA is metastable and thus, the seeding and ageing effects in the synthesis of zeolite NaY were investigated to avoid the formation of zeolite A or P as the impurities in zeolite NaY. Zeolites NaX and NaA were also successfully synthesized with high purity, absence of impurities and other phases, and high reproducibility. Thus, the amorphous forms of silica in RHA can be used as a source of silica for the synthesis of faujasite-types and NaA-type of zeolites.     

高活性稻壳灰的制备、提纯及应用的研究进展

稻壳灰是通过煅烧稻壳得到的一种高活性的火山灰材料,有着广泛而重要的用途。这里根据国内外研究现状及发展趋势,综述了高活性稻壳灰的制备、提纯及应用,特别就以稻壳硅为硅源的应用给予了重点阐述,并结合本课题组的研究,提出了稻壳灰的应用体会和展望。