Separation of Crotonic Acid and 2-Pentenoic Acid Obtained by Pyrolysis of Bio-Based Polyhydroxyalkanoates Using a Spinning Band Distillation Column
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Searching for renewable alternatives to produce platform chemicals, various biomasses have shown great potential as feedstock for value-added chemicals. For instance, biomass obtained by aerobic digestion of wastewater is rich in the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Pyrolysis of PHBV yields a mixture of crotonic acid (CA) and 2-pentenoic acid (2-PA). Application of CA and 2-PA as bio-based monomers requires purification. Purification by distillation is challenging as the high melting point of CA (72 °C) in combination with the high polymerization potential limits the temperature window for distillation severely. This study has experimentally explored the use of a spinning band distillation column (SBC) under vacuum operation to separate these acids. The thermodynamic feasibility for distillation was first studied by measuring vapor–liquid equilibrium data at relevant pressures of 50 and 100 mbar. The separation in the SBC was accomplished at 50 mbar and 40–110 °C for about 5 h. A successful recovery of CA with a high purity of >98% was achieved using a synthetic mixture of acids with a mass ratio of 80/20 (CA/2-PA). Actual pyrolyzate mixtures obtained by pyrolysis of the biomass and extracted pure PHBV were also fed to the distillation column and resulted in separation of CA with purities of 96 and 93%, respectively.Keywords:
Pyrolysis oil
Purification of production residue of 1,4-butanediol by vacuum batch distillation was studied.The vacuum of overhead,reflux ratio and heating load of the refining process were investigated.The suitable operating conditions of the refined process were obtained.Under the experimental conditions,the pressure of overhead was at 700 Pa,temperature of the bottom ranging from 160 ℃ to 170 ℃ and the whole process operating with variable reflux ratio.The results showed that the purity of final product(mass fraction) was more than 99.5% and the distillation yield was more than 80%.The method is stable,convenient for control and easy to be realized in industrialization.
Batch distillation
Residue (chemistry)
1,4-Butanediol
Continuous distillation
Mass fraction
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7-hydroxy is rectified by vacuum distillation with high efficient packed tower with θ filler,the product purity is over 98.5%,99.99% at instant,the yield is over 70%.Through the study of multivariable batch distillation process,the optimized operation parameters were obtained,the pressure is 2kPa—8kPa,the reflux ratio is 4—12.The experimentation indicated that multivariable batch distillation process could improve the yield.
Batch distillation
Continuous distillation
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2,3-Dichloro-5-trifluoromethylpyridine is rectified by vacuum distillation with high efficient packed tower with θ filler,the product purity is over 99%,99.3% at instant,the yield is over 75%.Through the study of multivariable batch distillation process,the optimized operation parameters were obtained,the pressure is 10kPa～30kPa,the reflux ratio is 4～1 2,The experimentation indicated that multivariable batch distillation process could improve the yield.
Batch distillation
Continuous distillation
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This paper studied the method of auxiliary additives in purification 1,8-Cineol by vacuum batch distillation according to the small boiling point difference between the components within the system of eucalyptus oil.The surface tension,phase equilibrium and validation experiments showed that adding additives could change the relative volatility between the 1,8-cineole and light elements,and thus improve the efficiency of purification of 1,8-cineole.By observing influences of the degree of vacuum,heating load,the reflux ratio and other operating factors on the separation effect,the appropriate operating conditions were determined.With additives Y under vacuum 1.770 kPa,the light fraction was collected during bottom temperature 51—54℃and total reflux for 30 minutes,and for the main components,bottom temperature were 57—60℃,and reflux ratio from 10 to 20.Experimental results showed that 1,8-cineole (its content89%and yielding rate 65.25%) could come out through the batch distillation.T he whole process were stable and good for commercial purposes.
Batch distillation
Boiling point
Continuous distillation
Relative volatility
Fraction (chemistry)
Steam distillation
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Benzoic acid
Benzyl benzoate
Batch distillation
Residue (chemistry)
Fluorenone
Oxidizing agent
Sodium benzoate
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A process for preparing cinnamaldehyde from cinnamon oil using vacuum distillation and molecular distillation was investigated.The optimum conditions of the process for obtaining high-purity and high-yield product were determined by analyzing the relative content of cinnamaldehyde with gas chromatography.The condition of vacuum distillation was as follows: pressure 1.333kPa,temperature of total reflux 60-70℃,temperature of collecting the light component 60-100℃,temperature of collecting the middle component 90-115℃,temperature of collecting crude cinnamaldehyde 110-125℃,reflux ratio 2∶1.Under these conditions,the purity and yield of the final product were 98.66% and 84.68%,respectively.The purity and yield reach 99.5% and 85.63% respectively after molecular distillation.
Steam distillation
Continuous distillation
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With atmospheric residue as raw material,8 narrow fractions of vacuum gas oil( VGO) and1 fraction of vacuum residue were obtained by molecular distillation and high vacuum distillation respectively. Distillation curves of the two distillation methods were plotted,and the property parameters of the cut fractions,such as density,refractive index,average relative molecular mass,dynamic viscosity and element content were compared. The results showed that molecular distillation had higher yield than high vacuum distillation at the same distillation temperature,and the yield difference between the2 distillations was up to 2. 22 percent points in350-540 ℃. With increasing the cutting temperature,the properties of these two series of cut fractions,such as density,refractive index and average relative molecular mass increased,which exhibited similar changing trends.
Continuous distillation
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Purification of the commercial plasticizer D. O. S. was carried out on the rate of distillation, 4050 cc/hour at 190200°C, with the continuous high-vacuum distillation apparatus having been described in the preceding report.Yield was 70%, and the obtainable final vacuum was 1.52.0×10-1mmHg at 180190°C, Then, for the binary mixture of pure D. O. S. and D. O. P. (di-2-ethylhexyl phthalate), the fractionation efficiency of this apparatus on the various distillation conditions were studied.
Continuous distillation
Batch distillation
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Crude distillation unit is the first process of the petroleum process,and it's very important to the subsequence units and the whole refinery plant.Even the simulation technology has been the most important method of the process analysis,the veracity of the simulation is the bottleneck.For primary distillation tower,atmospheric distillation tower and vacuum distillation tower of steady-state process simulation,the final process simulation result was extremely similar to the actual process parameters by selecting appropriate mid-cycle set variables of distillation tower and vacuum distillation tower simulation methods.The result shows that the atmospheric vacuum distillation process simulation can accurately reflect the actual process state,and it can serve as an effective way to guide production and operation optimization.
Process Simulation
Refinery
Batch distillation
Continuous distillation
Multiple-effect distillation
Dynamic simulation
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The fraction of benzyl benzoate and fluorenone were enriched from benzoic acid residua by flash distillation,then separated by vacuum batch distillation,so the recovery of benzoic acid residua was implemented.The experiment showed that this separation method is feasible and benzyl benzoate with purity about 90% and fluorenone products with purity of more than 85% were obtained.Furthermore the effects of tower top pressure,temperatures of tower top and bottom,reflux ratio on product purity were analyzed.The optimal operating condition was determined in the experimental condition.
Benzoic acid
Fluorenone
Benzyl benzoate
Fraction (chemistry)
Batch distillation
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