Study On Catalytic Pyrolysis Of Biomass For Acetol And Its Separation

Acetol had a very high value as a component of bio-oil, and it was a important drug intermediate. However, the content and purity of acetol were both not high. Biomass catalytic pyrolysis and researching separation methods of acetol can obtain acetol selectively. In this paper, acetol was the target product; microwave pyrolysis was used to investigate the catalytic effect of a variety of catalysts, and ion exchange resin was used to separate acetol. Conclusions were as follows:K2CO3, Na2CO3, KOH, NaOH as additives were used to pyrolyse poplar particles by microwave pyrolysis, and the influence of the amount of additive on pyrolysis conditions was investigated. The results indicated that:the catalysts both decreased the yield of the liquid, increased the yield of the solid; with the increasing of the amount of catalyst(2%,4%,8%), the yield of the liquid all decreased and the yield of the solid all increased; with the same amount of catalyst, the yield of the liquid was according to the order of Na2CO3>KOH>NaOH>K2CO3. However, the ability of choosing acetol was according to the order of K2CO3>KOH>NaOH>Na2CO3; when the amount of additives up to 4%, the content of acetol was not improved significantly.When a solid base K2CO3/Al2O3 was used to pyrolyse poplar particles by microwave pyrolysis, the total alkalinity of K2CO3/Al2O3 is larger, the yield of the liquid is smaller, the yield of the solid is larger, which did good to the generation of acetol. When the calcination temperature is 650? and the loading amount is 22.9%, the total alkalinity of catalyst reaches up to 1.923 mmol/g, the yield of the liquid reached minimum value of 23.55%, the yield of the solid reached maximum value of 36.38%, the content of acetol reached maximum value of 49.81%. According to the dynamic experiment of K2CO3/Al2O3 pyrolyse cellulose, the total alkalinity of K2CO3/Al2O3 was greater, the weight loss rate of cellulose pyrolysis was smaller, pyrolysis reaction activation energy of cellulose pyrolysis was lower. When the calcination temperature is 650? and the loding amount is 22.9%, the weight loss ratio and the pyrolysis reaction activation energy both reached minimum values of 84.2% and 149.6 kJ·mol-1, respectively. The dynamic equation was d?/dT= 4.39×10e-17994/T(1-?).In the part of separation of acetol, the HGA showed a better adsorption property among the six kind resins of HGA, IRA-67, HPD-100, AM-1, ADS-17,717. In the static adsorption experiment, the adsorption equilibrium time was 100min, the adsorption rate of acetol and acetic acid were 92.3% and 62.1%, respectively. In the range of 5?35?, with the increasing of temperature, the adsorption rate of acetol and acetic acid both increased based on HGA, but the wood vinegar would deteriorate easily owing to the temperature is too high, so the best static adsorption temperature was 25?In the dynamic adsorption experiment, the results showed that lower flow rate and higher temperature were beneficial for adsorbing acetol and acetic acid. Through a comprehensive consideration, the suitable conditions were as follows:the flow rate 5ml/min, temperature 25?In the dynamic desorption experiment, lower flow rate and lower temperature were beneficial for desorbing acetol and acetic acid. Desorbing by distilled water first, the suitable conditions were as follows:the flow rate 4ml/min, temperature 20?, on this condition the desorption rates of acetic acid and acetol are 91.0% and 27.5%, and the difference is maximum. Desorbing by ethanol solution secondly, through a comprehensive consideration, the suitable conditions were as follows:ethanol concentration 100%, the flow rate 4ml/min, temperature 20?, on this condition, the best desorption rate of acetol is 88.0%, the desorption rate of acetic acid is only 1.5%.