叶黄素的热解产物分析

为研究叶黄素对卷烟燃吸品质的影响,分别在300、600、900℃和氮气、10%氧气 90%氮气、大气环境中进行了叶黄素热解试验,热解产物经固相微萃取后进行GC/MS分析,并用叶黄素进行了卷烟加香试验。结果表明:①在所试验的温度和氛围中,叶黄素的裂解产物主要是甲苯、对-二甲苯、1,2-二氢-1,1,6-三甲基-萘和2,7-二甲基萘等,另外还有少量的氧化异佛尔酮、巨豆三烯酮、醛和烯烃类物质等;②叶黄素裂解产物的种类和相对含量都随着裂解温度的变化而变化,而裂解氛围则影响不大;③添加叶黄素的卷烟烟气香气略增加,但其杂气、刺激性都明显增大,余味变差。因此,添加叶黄素不利于卷烟抽吸品质的提高。     

热裂解-气相色谱质谱联用法快速检测聚丙烯材料中5种抗氧剂

采用热裂解气质联用仪,建立了一种无需任何样品前处理、全程无溶剂的、同时对5种常用塑料抗氧剂的定量分析方法.结果表明:通过该方法分析的5种常用抗氧剂,在0.2～1μg之间有很好的线性关系,且该方法操作简单、 快速准确,填补了热裂解气质联用技术在塑料助剂定量分析的空白.     

An optimization study on the pyrolysis of polystyrene in a batch reactor

The pyrolysis process of polystyrene (PS) has been investigated to find optimal temperature profiles which minimize the reaction time and the reaction energy required for a given conversion in a batch reactor. Assuming that the fragmentation of PS in pyrolysis is described by the mechanism of random and/or specific degradations, we used a continuous kinetic model for solving three moment equations to determine the transient change of molecular weight distributions (MWD) of the polymers. We then converted this independent-variable minimization problem using a coordinate transformation to a dependent-variable minimization problem that yields the optimal temperature profiles as its solution. The optimization results obtained in this study encompass the cases of different objective functions which cover minimum reaction time, minimum energy consumed, or any combination of these. It has turned out that maintaining the reaction temperature constant at an optimal level is the best solution in this optimization problem. An economic cost function also has been introduced as the third objective function to be minimized in addition to the reaction time and the reaction energy. This new function can serve as a convenient measure to judge the performance of the pyrolysis process minimizing the involved cost.     

生物质制取燃油催化裂解的工艺研究

通过实验证实,利用生物质甘蔗渣作为原料,在CaO作为催化剂和隔氧条件下发生催化裂解反应生成生物质燃料油的研究是可行的。影响生物质催化裂解生成生物质燃料油的两个最主要的因素：一个是裂解的温度,另外一个是催化剂CaO的用量,通过实验找出了这两个因素的最佳点,即：裂解温度为550℃,CaO与甘蔗渣的质量比约为0.15：1。通过对产品生物质燃料油进行真空蒸馏,分别在25℃、30℃、40℃、45℃下蒸馏出燃料油,再对蒸馏出的燃料油进行粘度和闪点的测定,它们的运动粘度（mm2/s）分别为2.31、2.89、3.45、5.38,它们的闪点分别为69℃、75℃、86℃、106℃。产品生物质燃料油的粘度和闪点位于我们所用的燃料油的安全粘度和闪点的范围内,可以满足作为燃料油的需要。     

Pyrolysis characteristics of Oriental white oak: Kinetic study and fast pyrolysis in a fluidized bed with an improved reaction system

The kinetic parameters for the pyrolysis of Oriental white oak were evaluated by thermogravimetric analysis (TGA). The white oak was pyrolyzed in a fluidized bed reactor with a two-staged char separation system under a variety of operating conditions. The influence of the pyrolysis conditions on the chemical and physical characteristics of the bio-oil was also examined. TGA showed that the Oriental white oak decomposed at temperatures ranging from 250 to 400 °C. The apparent activation energy ranged from 160 to 777 kJ mol^− 1. The optimal pyrolysis temperature for the production of bio-oil in the fluidized bed unit was between 400 and 450 °C. A much smaller and larger feed size adversely affected the production of bio-oil. A higher fluidizing gas flow and higher biomass feeding rate were more effective in the production of bio-oil but the above flow rates did not affect the bio-oil yields significantly. Recycling a part of the product gas as a fluidizing medium resulted the highest bio-oil yield of 60 wt.%. In addition, high-quality bio-oil with a low solid content was produced using a hot filter as well as a cyclone. With exception of the pyrolysis temperature, the other pyrolysis conditions did not significantly affect the chemical and physical characteristics of the resulting bio-oil.     

Additive and pyrolysis atmosphere effects on polysiloxane-derived porous SiOC ceramics

Porous silicon oxycarbide (SiOC) is emerging as a much superior ultrahigh surface area material that can be stable up to high temperatures with great tailorability through composition and additive modifications. In this study, bulk SiOCs were fabricated from a base polysiloxane (PSO) system by using different organic additives and pyrolysis atmospheres followed by hydrofluoric acid (HF) etching. The additives modify the microstructural evolution by influencing the SiO₂ nanodomain formation. The SiOC ceramics contain significantly less SiC and more SiO₂ with Ar + H₂O atmosphere pyrolysis compared to Ar atmosphere pyrolysis. Water vapor injection during pyrolysis also causes a drastic increase in specific surface areas. The addition of 10 wt% tetraethyl orthosilicate (TEOS) with Ar + H₂O pyrolysis produces a specific surface area of 1953.94 m²/g, compared to 880.09 m²/g for the base PSO pyrolyzed in Ar. The fundamental processes for the composition and phase evolutions are discussed as a novel pathway to creating ultrahigh surface area materials. The ability to drastically increase the specific surface area through the use of pyrolysis atmosphere and organic additives presents a promising processing route for highly porous SiOC ceramics.     

Products properties from fast pyrolysis of enzymatic/mild acidolysis lignin

The conversion of enzymatic/mild acidolysis lignin (EMAL) isolated from moso bamboo to aromatic chemicals by fast pyrolysis were investigated under nitrogen atmosphere and atmospheric pressure. The experiment of EMAL pyrolyzing was set on a tubular reactor furnace at the temperature levels of 400, 500, 600, 700, 800 and 900 °C, and the products derived from EMAL pyrolyzing were classified into three-phase of gas, condensed liquid (tar), and solid (char). The chemical structure and surface morphology of solid product were characterized by fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the ingredients of gas product and liquid (tar) were analyzed with gas chromatography (GC) and gas chromatography/mass spectrometer (GC/MS). The analysis results indicated that the yield of char decreased rapidly from 43% to 28% with an increase of temperature, and the yield of gas product increased gradually from 6% to 26%, and the yield of tar attained a maximum at 700 °C. SEM showed that char took on lots of vesicles that resulted from the gas release from EMAL pyrolyzing. The ingredients of gas product were comprised of H₂, CO, CO₂ and light hydrocarbons (CH₄, C₂H₄ and C₂H₆), and the amount of H₂, CO were high. Besides a huge amount of phenols, the tar contained aromatic hydrocarbons, chain hydrocarbons, monoaromatic aromatic hydrocarbons and some ketones, and the carbon number of chemical compounds were C₆–C₁₀.     

Synthesis gas production by biomass pyrolysis: Effect of reactor temperature on product distribution

This paper describes mass, C, H, and O balances for wood chips pyrolysis experiments performed in a tubular reactor under conditions of rich H₂ gas production (700–1000 °C) and for determined solid heating rates (20–40 °C s⁻¹). Permanent gases (H₂, CO, CH₄, CO₂, C₂H₄, C₂H₆), water, aromatic tar (10 compounds from benzene to phenanthrene and phenols), and char were considered in the balance calculations. Hydrogen (H) from dry wood is mainly converted into CH₄ (more than 30% mol. of H at 900 °C), H₂ (from 9% to 36% mol. from 700 to 1000 °C), H₂O, and C₂H₄. The molar balances showed that the important yield increase of H₂ from 800 to 1000 °C (0.10 Nm³ kg⁻¹ to 0.24 Nm³ kg⁻¹ d.a.f. wood) cannot be solely explained by the analyzed hydrocarbon compounds conversion (CH₄, C₂, aromatic tar). Possible mechanisms of H₂ production from wood pyrolysis are discussed.     

无烟煤热解时气相含氮化合物析出规律研究

用高温沉降炉研究无烟煤煤粉在830℃、880℃和930℃时热解产物中HCN、NH3、N2O、NO及NO2的析出规律.结果表明,随着温度的增加,煤样中的氮析出HCN、NO、NO2、NOx和气相含氮化合物的转化率呈先减少后增加趋势;NH3的转化率先增加后减少,NOx前驱物的转化率逐渐增加,N2O的转化率逐渐减小.NOx前驱物是煤样热解的主要气相含氮产物.     

Adsorption of 4-chlorophenol by inexpensive sewage sludge-based adsorbents

Sewage sludge was used as precursor to develop a potential inexpensive adsorbent by both simple drying and pyrolysis. The resulting materials were evaluated as adsorbents for the removal of 4-chlorophenol (4-CP) from aqueous solution. The dried biosolids showed a BET surface area lower than 3 m²/g, which yield a maximum adsorption capacity of 0.73 mmol 4-CP/g at pH 5.0 and 15 °C. The carbonization of biosolids under relatively mild conditions allowed obtaining materials with BET surface area up to 45 m²/g, which led to a significant increase of the maximum adsorption capacity (1.36 mmol 4-CP/g). The high ash content of the starting material (23%, d.b.) limits the development of porosity on a total dry-weight basis. Adsorption data were well fitted to the Redlich–Peterson isotherm equation whereas the most commonly used Langmuir and Freundlich equations were less satisfactory probably because of the occurrence of summative adsorption phenomenon. A thermodynamic study of the adsorption showed the spontaneous and exothermic nature of the process. Thus, simple drying and carbonization provide two ways of valorization of sewage sludge through its conversion into inexpensive low-rank adsorbents potentially useful for the removal of some hazardous water pollutants, like chlorophenols and related compounds.