Biomass Fast Pyrolysis For Valuable Chemicals

Fast Pyrolysis is a promising technique to convert lignocellulosic biomass mainly into a liquid product known as bio-oil. However, conventional bio-oils were difficult for chemical recovery owing to the complex chemical composition. It was necessary to establish a new technology system for producing a stable quality bio-oil enriched of valuable chemicals. The relative simple bio-oil could be refineried by the existing refining system to achieve industrialization and practical application of chemicals, paving the way to further utilization biomass resource. The biomass feedstock and Pyrolysis conditions had a great influence on the chemical composition of bio-oil. Pretreat catalytic Pyrolysis were adopted to regular the process of fast Pyrolysis. The target product would be obtained by the promotion or inhibition certain specific reaction pathway. In this study, the effects of feedstock, pretreatment, and catalyst to the chemical components of the bio-oil were studied, to obain valuable chemicals enriched bio-oil.The first part is the feedstock’s effects study.In this study, cellulose, xylan, mill wood lignin (MWL), and rice-husk were prepared and their Pyrolysis experiments were carried out in Py-GC-MS system, respectively, to study the Pyrolysis mechanism of lignocelluloses biomass. Especially, three different MWL were obtained from coniferous biomass, broad leaved biomass, and grass biomass, separately. All of these three MWL’s Pyrolytic vapor products were main phenolic pchemicals. However, there were distinctwished difference amoung them. Coniferous MWL’s Pyrolytic phenolic chemicals were mainly guaiac base, while a small amount of hydroxyphenyl also contained. Broadleaf MWL’s Pyrolysis gave priority guaiac and lilacs phenols, plus a small amount of hydroxyphenyl phenol. Grass MWL’s Pyrolysis products contain all of the three kinds of phenol chemicals.Rice husk’s Pyrolysis was composed of cellulose, hemicelluloses, and lignin’s prolysis. Quantitative analysis showed that only acetic aced (AA)’s cotent is greater than 1.0% in the bio-oil’s organic compounds mass fraction. However, most of those components whose mass fraction content less than 1.0% are high value-added chemical chemicals, such as between adjacent methyl phenol, methyl phenol, etc.Protein, lipids and micro algae’s fast Pyrolysis experiment was carried out, analyzing the Pyrolysis product distribution. Both of protein and lipids’s Pyrolysis generated a large amount of hydrocarbons, a certain amount of phenolic compounds and a small amount of sugar dehydration. Protein’s Pyrolysis also generated nitrogen compounds, such as Pyridine and Pyrrole. Microalgae’s prolysis is mainly protein, fat and carbohydrates Pyrolysis, with a certain amount of Maillard reaction between the protein and carbohydrates from the algae. Compared with lignocellulosic biomass, algae are an excellent raw material for hydrocarbon production. Reslduts also shows that alsge is easier to be Pyrolysised, and the highest liquild products yield was obtained at 550 ℃.The second part is the pretreatment’s effects study, focusing on the acid washing and torrfaction.The effect of acid-washing on rice husk during the fast Pyrolysis process was studied in the PY-GC-MS device. The results show that the total peak area decreased when the Pyrolysis temperature was below 600 "C, but increased when the Pyrolysis temperature was higher than 600℃. The generation of LG and FF were significantly promoted by the acid-washing pretreatment while AA and 1,2-cyclopentanedione and Phenol significantly reduced. The acid-washing effects on the generation of several kinds of products show opposite effects at different Pyrolysis temperature. Their generations were promoted at lower Pyrolysis temperature while inhibited at higher temperature. The increase of the total product peak area was mainly contributed by the thermal decomposition of cellulose and hemicellulose.To study the effects of baking temperature on the Pyrolysis chemical products distribution, rice-husk smples were baked in a tube furnace, after then they were Pyrolyzed in the Py-CC-MS system. The results show that with the increase of baking temperature, the quantity of Pyrolysis vapor product components kinds reduced slightly.This should be caused by the baking process during which rice husk lost most hemicelluloses. The Pyrolysis products of hemicellulose decreased significantly or nven disappear, while the content of cellulose and lignin relatively increased. But when the baking temperature increased to 290 ℃, almost all of chemical products reduced. The relative content of phenolics compounds which originated from lignin increased, while both the relative content of cellulose and hemicellulose Pyrolysis products reduced.The third part is the catalyst’s effect to the chemicals production.In this study, ex-situ catalytic Pyrolysis using HZSM-5 zeolite catalyst was rich bio-char from sewage sludge. Pyrolysis temperature and catalysis temperature were investigated to obtain an optimal condition in terms of hydrocarbons production. The optimal Pyrolysis and catalysis temperatures were 500℃ and 600℃, respectively. Carbon yields of olefins and aromatic hydrocarbons were 24% and 19%, respectively. For comparison, lignocellulosic biomass (red oak) was tested under the same conditions, which produced maximum carbon yield of olefins and aromatic hydrocarbons of 15% and 19%, respectively. The fate of inorganic minerals during the process was also investigated. Negligible amounts of metals volatilized during Pyrolysis, suggesting that catalyst poisoning during Pyrolysis of sewage sludge may not be a major problem. This study suggests that catalytic Pyrolysis can be used to convert sewage sludge into value-added chemicals and nutrient-rich bio-char.The desilication of HZSM-5 was carried out using aqueous solutions of NaOH. The structure and acid property of HZSM-5 before and atter desilication were characterized by XRD. N2 sorptidn and TPD of ammonia. Meanwhile, the catalytic Pyrolysis of ccellulose was also tudled in a PY-GC-MS/FID system. Furthermore, the catalyst can remove most of the oxygen in the form of CO and CO2, thus it reduce the oxygen content in the biobgical oil effectively. Liquid yields of cellulose catalytic Pyrolysis and bio-oil cabrific value are 46.83% and 32.85 MJ.kg-1. The hydrocarbons yield refiched 40.34% (mass fraction), while the carbonyl and alcohols compounds decrease significantly.In this study, a two-stage catalytic fast Pyrolysis of rice-husk using Pd/SBA-15 (mesoporous structure) and HZSM-5 (microporous structure) in sequence is developed to produce high-quality fuel. The performance of the two-stage catalytic cracking is tested in the Pyrolysis-Gas Chromatography-Mass Spectrometry system. After catalysis, the main products are benzene, toluene, xylene, and naphthalene, while the primary oxygenated compounds are significantly reduced or even completely eliminated. Compared with the one-stage catalytic cracking over HZSM-5, the two-stage method presents some advantages because of the higher yield of hydrocarbons and the lower content of polycyclic aromatic hydrocarbon. The weight ratio of the two layer catalysts is critical in maximizing the hydrocarbon yield. When the weight radio of Pd/SBA-15 to HZSM-5 is set to 0.5, the yields of toluene and xylene increase by 46% and 73%, respectively, over the one-stage HZSM-5 catalytic cracking. Meanwhile, two polycyclic aromatic hydrocarbon compounds (naphthalene and 2-methyl-naphthalene) decrease by 46% and 31%, respectively. Reversing the sequence of catalysts does not show the same advantages. It indicates that the mesoporous structure and the loaded Pd of Pd/SBA-15 operate favourably to transform the biomass-derived oligomers into monomeric compounds, and they are further converted into monocyclic aromatic hydrocarbons on the acidic sites of HZSM-5.This study investigates the online catalytic cracking of lignin fast Pyrolysis vapors using MO2N/γ-Al2O3 prepared by nitriding an alumina-supported molybdenum oxide precursor with nitrogen hydrogen mixtures though temperature programming. The activity and selectivity of the catalyst toward aromatic hydrocarbons were determined in the Pyrolysis-gas chromatography/ mass spectrometry system. Results show that the catalyst has a significant function in the Pyrolysis process. In the presence of the catalyst, the primary Pyrolysis products from lignin are catalytically converted into aromatic products, benzene and toluene, as well as to an insignificant quantities of dimethylbenzene, ethylbenzene, trimethylbenzene, and naphthalene. The highest aromatic hydrocarbon yield of 17.5% is obtained using MO2N/γ-Al2O3 (the catalyst-to-lignin weight ratio = 4) at 700℃; by contrast, this yield is only 1.4% when no catalyst is used. Furthermore, the highest benzene yield of 70.1% is obtained using MO2N/γ-Al2O3 (catalyst-to-lignin weight ratio = 4) at 850 ℃. Under this condition, the monocyclic aromatic hydrocarbons together contribute > 95% of the total aromatic hydrocarbon yield, whereas the selectivity toward naphthalene is only 2.2%.Fours kinds of tobacco were studied in this paper with the aim of obtaining the special chemicals’s formation discipline. Results show that some kinds of special valuable chemicals which are difficult to synthesis, such as nicotine and phytol, were existed in the tobacco Pyrolysis vapor. Nicoting started to energe at 200 ℃ and its highest yield was obtained at 600 ℃, at which nicoting staterted to decompose. Its highest content was obtained at 300 ℃ 。 Another valuable chemical (phytol) staterd to emerge at 400 ℃, and increased with the rising temperature. Therefore, Pyrolysis could be a new potiential technology route for the production of such kinds of special natural chemicals from tobacco.There are lots amount of lignin existed in the papermaking black liquild. In this study, the lack liquid was put forward for the preparation of high value-added phenolic chemicals. The highest liquild yield (23%) was obtained at 600 ℃ Pyrolysis for black liquor lignin Pyrolysis. Results indicated that LG, methyl mercaptan, and dimethyl sulfide, were also observed in the black liqiled lignin Pyrolysis product, while MWL’s prolysis products did not contain. This should be due to the difference beween the two lignin feedstock, since Pyrolysis product is closely related to the raw material composition. In the black liqeld lignin, the black liqid still contain some oligosaccharides, organic acid and alkali metal salt, which can affect the Pyrolysi process. Therefore, to adjust its chemical composition, to appropriate pretreatment of black liquid, to a large extent can control the composition of the Pyrolysis products.The waste paper was mainly composed of cellulose and hemi-cellulose, both of which were furan compounds formation raw material. In this study, paper was Pyrolysised at different temperature, with the aim of obtaining highest liquid yield. Results show that 55O℃ gavethe highest liqid yield, and the main components in the liqid were androsugar and fiirans. By the introduction of ZnCl2 catalyst, the selectivities for furans inproved significantly.The process of selective catalytic Pyrolysis can be further extended to more extensive biomass feedstocks. In addition to acetic acid, furfural and other bulk chemicals, levoglucosenone and other high value-added chemicals could also be obtained. It would not only solve the higher economic cost of biomass utilization, but also achieve high-value utilization of biomass resources. Promotion of the process would have good economic and social benefits.