| Fast pyrolysis technology can convert agriculture and forestry’biomass waste into liquid bio-oil. Crude bio-oil has several disadvantages, such as high water content, low heating value, corrosivity and high viscosity. It is necessary to be upgraded before high-grade transport fuel application. Bio-oil upgrading process has been holden back for a long time because of its complex components. To accelerate the high-grade application process of bio-oil the present paper put forward a new upgrading route that is conducting the bio-oil upgrading researches on its molecular distillation fractions.Molecular distillation technique was first adopted by us to carry out the efficient separation of bio-oil. It indicated that the thermal sensitivie bio-oil was successfully separated into bio-oil fractions without coking problems.. During bio-oil molecular distillation procedures, separation characteristics of single distillation process and multiple distillation procedures were investigated. Physical properties and compounds distribution characteritics of bio-oil fractions were studied. Furthermore, separation factor model was proposed to evaluate the separation characteristics of compounds in bio-oil. It was found that cyclopentenone, hydroxyl-acetone, acetic acid and furfural showed good distillation characteristics and were easy to be enriched in the distilled out fractions.Combined with bio-oil fractions from molecular distillation process, upgrading researches by catalytic esterification technology, catalytic cracking technology and emulsifying technology were carried out. During the esterification upgrading of bio-oil fractions, solid acid catalyst was prepared with washing pretreatments. Solid acid catalysts with high activity and stability were prepared. The esterification refinement of bio-oil fraction was done with optimal solid acid catalyst. It showed that the content of carboxylic acids reduced from18.39%to2.70%in upgraded bio-oil fraction, and its ester content increased to31.17%. In the catalytic cracking researches. concept of effective hydrogen to carbon ratio was introduced, and the co-cracking of compounds in bio-oil with ethanols was done. When cyclopentanone and hydroxyl-acetone were cracked separately without ethanols. HZSM-5molecular sieve was easy to deactivate, and the content of liquid hydrocarbons in the cracking products was also very low. However, when methanol or ethanol was introduced as co-cracking reactant. the conversion yield of cyclopentanone and hydroxyl-acetone reached100%. Light yellow gasoline phase was also produced. Based on the good results from of ketones cracking, co-cracking of acetic acid and ethanol was also further developed. Acetic acid got a conversion rate of100%, and a high gasoline phase yield up to42.79wt%was also obtained. Based on cracking research on bio-oil model compounds, the gasoline production research by cracking of bio-oil fractions was attempted. The co-cracking procedure of bio-oil fractions and ethanol ran steadly, and successfully procuded gasoline phase with a yield of26.7wt%. Besides, emulsions preparation between bio-oil fractions (middle fraction and heavy fraction) and0#diesel was investigated by mechanical emulsification and ultrasonic emulsification technologies. In the condition of mechanical emulsification accompanied with ultrasonic emulsification, emulsion preparation characteristics among crude bio-oil, middle fraction and heavy fracion were compared. It was found that emulsion produced from crude bio-oil had the longest stabilization time. Emulsion produced from heavy distillates had the shortest stabile time as a result of the big density dfference between heavy fraction and diesel. Based on comparation of emulsion stability between bio-oil fractions and crude bio-oil, an emulsification model was raised to explain their differences in emulsion properties. |
PDF Full Text Request