酸式盐催化玉米芯水解制取糠醛的工艺优化

针对工业生产中采用稀硫酸催化玉米芯水解制备糠醛存在催化剂毒性大、腐蚀及污染严重等问题,本研究尝试采用酸式盐催化玉米芯水解制备糠醛。通过单因素试验研究了催化剂种类、反应时间、反应温度对糠醛得率的影响。确定了制取糠醛的最佳工艺条件为硫酸氢钠作催化剂、反应时间90 min、反应温度190℃,此条件下糠醛的得率达39.91%。     

1,3-二磺酸根咪唑四氯化铝盐催化葡萄糖脱水制备5-羟甲基糠醛

1,3-二磺酸根咪唑四氯化铝盐{[Dsim]AlCl₄}作为一种新型的磺酸根咪唑盐,同时具有布朗斯特酸和路易斯酸性质。本文合成了1,3-二磺酸根咪唑四氯化铝盐,并将其用于催化葡萄糖转化为5-羟甲基糠醛（5-HMF）的反应。研究表明：反应温度、反应时间和催化剂用量对催化葡萄糖转化为5-HMF这一反应起着重要的影响,提高反应温度能够缩短反应时间,进一步延长反应时间,5-HMF的产率反而减少。在最优化的条件下（140℃,30 min）,5-HMF的产率可达52.1%。此外,动力学分析揭示了{[Dsim]AlCl₄}在DMSO中催化葡萄糖转化为5-HMF的反应为二级反应,并计算出其活化能为138 kJ•mol^-1。本研究对咪唑金属盐催化转化葡萄糖制备5-HMF具有一定的指导意义。     

纤维素亚临界和超临界水液化实验研究

在温度为340～420℃、压力为30～40MPa的实验条件下，对亚临界和超临界水中纤维素液化进行实验研究，液化产物经GC—MS分析，得到其主要成分是糠醛、5-甲基糠醛、5-羟甲基糠醛和一些含甲基、羟基、羟甲基等官能团的酮类、苯酚类化合物，且反应温度变化时，液化产物成分和浓度有较大变化；对纤维素液化转化率有重要影响的两个因素——反应温度和纤维素与水质量比进行初步实验研究，结果表明：(1)反应温度为380℃左右。液化转化率最高；(2)纤维素与水的质量比为1：15左右，转化率达最大值。     

CO2-高温液态水体系下果糖分解制备5-羟甲基糠醛的研究

5-羟甲基糠醛(5-HMF)是一种重要的化工中间体,具有非常广泛的应用价值和市场前景。在CO2-高温液态水体系下,探讨了二氧化碳初始压力、反应温度以及果糖初始浓度等因素对果糖制备5-HMF的影响。结果表明,CO2-高温液态水催化体系对果糖脱水分解制备5-HMF具有较高的催化活性,在果糖初始浓度高达10%时也可获得较好的5-HMF收率。在果糖浓度为3%,CO2压力为5.0 MPa,160℃的条件下反应100 min,5-HMF的收率为54.3%,反应生成5-HMF的选择性高达57.7%,催化活性为无CO2的高温液态水的2～3倍。CO2压力对果糖分解制备5-HMF有重要影响,随着体系中CO2压力的增加,5-HMF的收率也逐渐增加,但生成5-HMF的选择性有所下降。     

废纸纤维近临界水解获取5-羟甲基糠醛的研究

以废纸纤维为原料,研究温度、反应时间、原料浓度、反应压力对废纸纤维近临界水解获取5-羟甲基糠醛(5-HMF)的影响,同时考察前驱物六碳糖和水解副产物乙酰丙酸对5-HMF生成和降解的影响。最优水解条件显示:近临界温度为375℃、反应时间为200 s、原料浓度为2.4%、反应压力为19.2 MPa时,获得的5-HMF产率最大,为(10.92±0.51)%。相比原生废纸纤维,其水解残渣的结晶度由69.24%降为57.14%,残渣中仍存在一定量的纤维素,纤维素结晶结构带来的反应屏障是影响5-HMF产率的一个重要因素。     

稀酸和氨相结合预处理柳枝稷

为了提高柳枝稷中纤维素和半纤维素糖的转化率,降低水解液中抑制剂的浓度,采用稀酸低温水解和氨浸泡相结合的方法对柳枝稷进行预处理.通过对酸、氨浓度、液固比、反应时间、温度的研究,确定两步法预处理的最佳条件.经两步预处理和Celluclast 1.5L,Novozyme 188酶解,总纤维素(葡萄糖)转化率为85.99%;半纤维素(木糖)的转化率为66.99%;总糖转化率为77.26%,稀酸水解液中抑制剂的浓度较低,乙酸为2.20g,L,糠醛为1.37g/L,检测不到5-羟甲基糠醛.研究结果为利用柳枝稷制取燃料乙醇提供了新途径.     

纤维素类碳水化合物转化为糠醛的研究进展

糠醛是一种用于制备高附加价值液体燃料和其他精细化学品的重要的生物质平台化合物。通常,木质纤维素中的半纤维素在水介质中经酸催化剂作用解聚得到五碳糖后进一步脱水可转化为糠醛,该工艺技术已趋于成熟并用于工业化生产。纤维素在水或一般的双相反应体系中解聚为六碳糖后脱水通常生成5-羟甲基糠醛与乙酰丙酸,而难以甚至不能转化为糠醛。最近的一些文献报道了纤维素类碳水化合物在特定的反应介质中经酸催化剂作用后可转化为糠醛,且提出了不同的反应历程。基于当前研究背景,本文针对纤维素类碳水化合物转化为糠醛的反应特点,综述了已有报道中纤维素类碳水化合物转化为糠醛的反应机理、反应路径和反应体系的特点及反应介质对该反应的影响。最后,对未来纤维素类碳水化合物转化为糠醛的研究方向和发展前景进行了展望。     

废油脂制取生物柴油的工艺优化及其品质提升

在碱性催化剂作用下,对废油脂制取生物柴油的工艺优化及品质提升方法进行了研究.考察了原料油水分含量、醇油物质的量比、催化剂浓度、反应温度、反应时间等对转酯化反应的影响,以及水洗、酸洗、萃取、减压蒸馏等不同后处理方法对产品品质的影响.在醇油物质的量比为9:1、催化剂质量分数为1.3%、反应温度为50℃及反应时间为90 min的条件下,所得样品通过常压、减压蒸馏相结合的后处理方法,可以获得品质良好的生物柴油样品.     

固体碱催化猪油制备生物柴油

运用实验研究和理论分析相结合的方法,阐述猪油和甲醇在CaO催化剂作用下进行酯交换反应制取生物柴油的基本原理和操作方法,分光光度法测定甘油含量,计算生物柴油转化率,得出以CaO催化猪油制取生物柴油的适宜反应条件。结果表明:CaO做催化剂时,催化剂用量为2.0%,醇油物质的量比为6∶1,反应时间为150min,温度为60℃进行磁力搅拌,反应产率最高可达93.68%。     

固体酸和两相反应体系对糠醛制备的影响

糠醛是一种重要的生物质基平台化合物,在医药、农药、橡胶和石油炼制等领域有着广泛的应用,其开发具有广阔的市场前景。目前,糠醛的制备主要是以生物质中的半纤维素为原料,经过解聚和脱水反应获得。本文综述了以生物质及木糖为原料催化制取糠醛的反应机理,以及采用不同固体酸催化剂和反应溶剂体系生产糠醛的研究进展,为利用生物质生产糠醛提供技术参考。     

Conversion of fructose and glucose into 5-hydroxymethylfurfural catalyzed by a solid heteropolyacid salt

A solid heteropolyacid salt Ag₃PW₁₂O₄₀ has been used as a heterogeneous catalyst for the production of 5-hydroxymethylfurfural (HMF) from fructose and glucose. The fructose was selectively dehydrated into HMF with the HMF yield as high as 77.7% and selectivity of 93.8% within 60 min at 120 °C. In addition, Ag₃PW₁₂O₄₀ also exhibited catalytic activity for conversion of glucose into HMF. Moreover, the catalyst is tolerant to high concentration feedstock and can be recycled. The results illustrate that the Ag₃PW₁₂O₄₀ is an excellent acid and environmentally benign solid catalyst for the production of HMF from fructose and glucose.     

Study of Mo-based sepiolite catalyst on depolymerization of lignin under supercritical ethanol

A unique Mo/SEP catalyst using low-cost and available sepiolite as support was prepared by wet impregnation method. All catalyst performances of the Mo/SEP catalysts were studied in process of lignin catalytic depolymerization (LCD) under supercritical ethanol with nitrogen pressure, and the effects of reaction temperatures and reaction time on LCD process were also investigated. X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy techniques were used to characterize the structural characteristics of the fresh and spent catalysts, and gas chromatography-mass spectrometry (GC-MS) was employed to analyze the compositions of the obtained liquid product. The results indicated that Mo/SEP catalyst had unique performance for LCD, and the highest soluble fraction yield of petroleum ether of 47.6% and yield of liquid product of 63.5% were obtained with constantly reacting for 4 hours at 290°C and 6.5 MPa N₂. In addition, relevant characterizations demonstrated that the reaction temperature could cause the phase transfer of catalyst and change of Mo⁶⁺ to Mo⁵⁺ species. The conversion degree of Mo⁶⁺ to Mo⁵⁺ was the major reason responding for the catalytic performance of Mo/SEP catalyst during LCD process.     

新型泥煤生物炭基催化剂催化甘油酯交换合成碳酸甘油酯

以泥煤生物炭为原料,制备了一系列廉价、高效的固体碱复合催化剂,用于催化甘油和碳酸二甲酯进行酯交换反应制备碳酸甘油酯。通过扫描电子显微镜（SEM）、X射线能谱（EDS）、X射线衍射（XRD）、N2吸脱附（BET）、热重分析（TG）及Hammett指示法对催化剂进行表征。同时对催化剂的制备条件、催化反应条件及重复利用进行了分析。结果表明：催化剂30K/PB-600具有最优催化活性,当催化剂用量为5wt%、碳酸二甲酯/甘油摩尔比为4∶1、反应时间为90 min、反应温度为80℃ 时,甘油的转化率达到99.1%,碳酸甘油酯的产率达到95.7%;经过5次循环利用后,甘油的转化率为94.2%,碳酸甘油酯的产率为69.8%,产率下降的原因主要是由于K+ 的流失。     

Waste capiz (Amusium cristatum) shell as a new heterogeneous catalyst for biodiesel production

The waste Capiz shell was utilized as raw material for catalyst production for biodiesel preparation. During calcination process, the calcium carbonate content in the waste capiz shell was converted to CaO. This calcium oxide was used as catalyst for transesterification reaction between palm oil and methanol to produce biodiesel. The biodiesel preparation was conducted under the following conditions: the mole ration between methanol and palm oil was 8:1, stirring speed was 700 rpm, and reaction temperature was 60 °C for 4, 5, and 6 h reaction time. The amount of catalyst was varied at 1, 2, 3, 4, and 5 wt %. The maximum yield of biodiesel was 93 ± 2.2%, obtained at 6 h of reaction time and 3 wt % of amount of catalyst. In order to examine the reusability of catalyst developed from waste of capiz (Amusium cristatum) shell, three transesterification reaction cycles were also performed.     

Synthesis and characterization of monk fruit seed (Siraitia grosvenorii)-based heterogeneous acid catalyst for biodiesel production through esterification process

This research investigated for the first time the synthesis of monk fruit seed (Siraitia grosvenorii)-based solid acid catalyst for biodiesel production. The catalyst was synthesized using a two-step surface functionalization method with trimethoxy phenyl silane and chlorosulfonic acid. The as-synthesized catalyst was characterized to ascertain its catalytic characteristics through surface morphology, chemical bonding, and thermal stability. The effects of activating agent impregnation ratio, carbonization temperature, and sulfonation temperature towards fatty acid methyl ester (FAME) yield were elucidated. The esterification reaction with palmitic acid was found to produce FAME yield up to 98.5% with 4 wt.% catalyst loading, 6-h reaction duration and 120°C reaction temperature. The catalyst also demonstrated high reusability with 84.4% FAME yield being successfully maintained after four successive cycles without reactivation. These proved that the as-synthesized catalyst had high prospect to become a suitable low-cost alternative for biodiesel production through catalytic esterification process in the future.     

Response surface analysis for optimisation of reaction parameters of biodiesel production from alcoholysis of Parinari polyandra seed oil

Availability of information on the efficiency of applied conditions to biodiesel synthesis from diverse seed oil can establish optimal biodiesel yield from favourable reaction variables. The effect of reaction parameters; temperature, time and catalyst amount, were varied on biodiesel yield from alcoholysis of Parinari polyandra oil using potassium hydroxide as catalyst. Maximum biodiesel yield of 95.62% was obtained from the experimental results. Analysis of Variance revealed that the reaction variables had significant effects on biodiesel yield. Data analysis predicted an optimal biodiesel yield of 92.75% at reaction conditions of 61.20°C temperature, 60 min, and 1?wt% of catalyst amount. Validation experiments of the optimal conditions gave an average biodiesel yield of 91.72%. The study established optimal conditions of temperature, time, and catalyst amount for biodiesel production from P. polyandra oil. The fuel properties of the biodiesel fell within the standards of the American Society for Testing and Materials D6751.     

Utilization of waste freshwater mussel shell as an economic catalyst for biodiesel production

An economic and environmentally friendly catalyst derived from waste freshwater mussel shell (FMS) was prepared by a calcination-impregnation-activation method, and it was applied in transesterification of Chinese tallow oil. The as-prepared catalyst exhibits a “honeycomb” -like structure with a specific surface area of 23.2 m² g⁻¹. The newly formed CaO crystals are major active phase of the catalyst. The optimal calcination and activity temperature are 900 °C and 600 °C, respectively. When the reaction is carried out at 70 °C with a methanol/oil molar ratio of 12:1, a catalyst concentration of 5% and a reaction time of 1.5 h, the FMS-catalyst is active for 7 reaction cycles, with the biodiesel yield above 90%. The experimental results indicate that the FMS can be used as an economic catalyst for the biodiesel production.     

Effect of cosolvent and addition of catalyst (HZSM‐5) on hydrothermal liquefaction of macroalgae

The present study aimed to evaluate the effect of the direct liquefaction of macroalgae in an autoclave reactor (50 mL) possessing water and ethanol as cosolvent. The reaction conditions such as duration, temperature, algae/solvent ratio, the composition of cosolvent (ethanol‐water) on product distribution, and bio‐oil characterization were studied. The optimum conditions such as 300°C of temperature, 45 minutes of reaction time, 75% of ethanol, and algae to solvent ratio of 4/40 g/mL supported the bio‐oil yield of 46.75% with a conversion rate of 95.5%. The composition and concentration of the compounds in the bio‐oil produced under various doses of catalyst were described using GC‐MS. The bio‐oil characterization showed that the esters were most predominant in hydrothermal liquefaction with a catalyst (HZSM‐5) compared with hydrothermal liquefaction in the absence of the catalyst.