Bio-asphalt has a great application prospect in the replacement of petroleum-based asphalt to pave and maintain asphalt pavement. However, the problems of flow-induced crystallization and phase separation caused by flowinduced crystallization had severely restricted its application. This paper describes the progress of research on preparation, property evaluation and phase separation mechanism of bio-asphalt. The advantages and disadvantages of preparation methods of bio-asphalt are states. The fundamental physical and rheological properties of bio-asphalt are investigated, especially for flow-induced crystallization. There exists obvious flow-induced crystallization because bio-asphalt is rich in waxes that crystallize easily. Owing to the existence of excess biochar,bio-asphalt appears phase separation. A brief review of the effect of bio-oil and biochar on asphalt volatile organic compounds(VOCs) is presented. Research find that bio-oil/biochar are not only replenish the light components of asphalt, but also improve the flow-induced crystallization and phase separation of bio-asphalt. There exists synergistic effect of biochar and bio-oil in asphalt modification. Moreover, biochar can improve the durability of bio-oil modified asphalt, but excessive addition of biochar to bio-oil modified asphalt can cause phase separation.Adding an appropriate amount of bio-oil and biochar to asphalt can improve its high-temperature resistance, lowtemperature crack resistance, and system compatibility.
The current energy crisis could be alleviated by enhancing energy generation using the abundant biomass waste resources. Agricultural and forest wastes are the leading organic waste streams that can be transformed into useful alternative energy resources. Pyrolysis is one of the technologies for converting biomass into more valuable products, such as bio-oil, bio-char, and syngas. This work investigated the production of bio-oil through batch pyrolysis technology. A fixed bed pyrolyzer was designed and fabricated for bio-oil production. The major components of the system include a fixed bed reactor, a condenser, and a bio-oil collector. The reactor was heated using a cylindrical biomass external heater. The pyrolysis process was carried out in a reactor at a pressure of 1atm and a varying operating temperature of 150˚C, 250˚C, 350˚C to 450˚C for 120 minutes. The mass of 1kg of coconut fiber was used with particle sizes between 2.36 mm - 4.75 mm. The results show that the higher the temperature, the more volume of bio-oil produced, with the highest yield being 39.2%, at 450˚C with a heating rate of 10˚C/min. The Fourier transformation Infrared (FTIR) Spectroscopy analysis was used to analyze the bio-oil components. The obtained bio-oil has a pH of 2.4, a density of 1019.385 kg/m3, and a calorific value of 17.5 MJ/kg. The analysis also showed the presence of high-oxygenated compounds;carboxylic acids, phenols, alcohols, and branched oxygenated hydrocarbons as the main compounds present in the bio-oil. The results inferred that the liquid product could be bestowed as an alternative resource for polycarbonate material production.
Patrick Ssemujju LubowaHiram NdirituPeter OketchJames Mutua
Replacing fossil carbon sources with green bio-oils is a promising route to switch to a sustainable chemical industry,although their high oxygen contents are challenging.Catalytic hydrodeoxygenation is a favored route to upgrade bio-oils to renewable fuels and basic chemicals.In this work,we investigated Ni/SiO2 catalysts with differing metal dispersity in continuous mode conversion of guaiacol with a statistical experimental design for 250℃to 400℃,2 h up to 5 h time on stream(ToS)and subsequently different residence time besides other parameters.While low temperature(250℃)promotes cyclohexanol formation from guaiacol,high temperature(400℃)inhibits hydrogenation,leading to phenol and methane.For medium temperature(340℃),the selectivity for cyclohexanone increases.Cyclohexanol and cyclohexanone(KA-oil)are the industrial basis for polyamide 6.Furthermore,we clarified the role of 2-methoxycyclohexanol(2MC)in the reaction network towards KA-oil for continuous-mode operation.Statistical analysis was used to predict and optimize product selectivity and yield,leading to the best yield of cyclohexanone/-ol at 327.5℃,low ToS,medium residence time,high particle dispersity,and medium hydrogen pressure(15 bar(g)).
Bio-oil is a major product from pyrolysis of biomass which serves as a carbon source to produce carbon material due to its high reactivity towards polymerization itself or cross-polymerization with other organic feedstocks.In this study,activation of polyaniline(PANI)mixed with wheat straw-derived bio-oil and K2C2O4 at 800°C was conducted,aiming to understand the effect of potential interactions of bio-oil with PANI on pore development of resulting activated carbon(AC).The results revealed cross-polymerization reactions between PANI and bio-oil during direct activation,which increased the yield of AC from 13.0%(calculated average)to 15.0%,the specific surface area from 1677.9 m^(2) g^(-1)(calculated average)to 1771.3 m^(2) g^(-1),and the percentage of micropores from 94.3%to 97.1%.In addition,pre-polymerization of PANI and bio-oil at 200°C before activation was also conducted.Such pretreatment could increase the AC yield from 13.0% to 23.3%,but the specific surface area decreased to 1381.8 m^(2) g^(-1).The pre-polymerization formed the organics that were more resistant towards cracking/gasification,but introduced oxygen-rich functionalities.This made AC highly hydrophilic,rendering a much higher capability for adsorption of phenol despite the smaller specific surface area.Additionally,the AC with developed pore structures facilitated dispersion of nickel in Ni/AC and enhanced the catalytic activity for hydrogenation of o-chloronitrobenzene and vanillin.
