Detection And Application Of Trace Oxygenates By GC×GC/MS During Biomass Refining Process

An over reliance on fossil fuels not only leads to excessive emissions of CO₂ which aggravates the Green House Effect,but also cause energy depletion.Hence,fully utilize renewable biomass resources to synthesize liquid fuel has become a major proposition in achieving China’s"dual carbon"goal.The biological refining system is to convert existing renewable biomass into products with high grade and added value,such as bio aviation fuel.Due to the complexity of biomass resources,the analysis of liquid products has always been a research hotspot in the field of biomass.Among various analytical means,comprehensive two-dimensional gas chromatography-mass spectrometry（GC×GC-MS）is a high resolution and sensitive technology with separation and identification.However,it still has many shortcomings for a deeper understanding of the reaction process and overall analysis of liquid products regarding biomass refining systems through GC×GC-MS,such as singleness of compound identification and co-elution of trace component,which needs substantial improvements.This paper focuses on trace oxygenates of the biomass refining process based on GC×GC-MS research platform.From the two aspects of analytical method establishment and application,it tailors a scheme for the separation and characterization of detailed components in liquid products,and provides theoretical and experimental basis for complex systems.The main work and results are accomplished as follows:（1）The methods of two-dimension retention time prediction and programmed temperature conditions optimization have been established.Prediction of retention time was achieved by constant current and isothermal experiment of common 17 common compounds（n-alkanes,cycloalkanes,aromatic hydrocarbons）in biological liquid fuel.In constant temperature condition and programmed heating conditions（heating rate and hold time）.The prediction results under isothermal condition（E%<4%）is more accurate than that under programmed temperature condition,because of the difficulty of accurately calculating the temperature at which the components flow out of the first column.On this basis,the optimum temperature program was designed by using the over-all resolution efficiency index（R>2.2）and the lowest temperature of components when the capacity factor k′=2,it can meet the separation requirement for all components in two columns and the testing time is the shortest.Finally,the effects of temperature program（initial temperature,heating rate and linear velocity）,modulator,stationary phase on GC×GC system separation were studied with light cycle oil as the research object.（2）A series of n-alkanes（C8-C20）were selected for constant current isothermal experiments,an equation for the relationship between column temperature,retention time and carbon number was obtained,which contained only four constants.Based on this equation,the isovolatility curves of n-alkanes were constructed,and 2I of n-alkanes were calculated under constant temperature condition and programmed temperature conditions respectively.The results showed that the curve had good performance.The 1I and 2I values of bio aviation fuel were obtained by Kratz index and isovolatility curves,and mass spectrometry data,93 components were preliminarily identified.The results showed that the combination of three dimensions（mass spectrometry data,1I and 2I）was more beneficial to the characterization of compounds,especially isomers.（3）The traditional 1DGC quantitative method was extended to GC×GC system.Jet fuel and bio aviation fuel as the research objects,normalization methods and internal standard method were respectively carried out,and the results of the two quantitative methods were compared.The results showed that the analysis results of two methods were not much difference under the premise that all components could flow out of two-dimensional columns in the same analysis period.On the other hand,it was more accurate for trace compounds to select internal standard method.（4）E-cat catalyst were used for bio-oil water soluble phase/VGO（0/100,10/90,20/80）co-cracking in the FCC unit under the different reaction temperature of 500℃ and 525℃.And the liquid products were separated and identified based on GC×GC-MS research platform,and the components of phenols in gasoline and benzofurans in LCO were analyzed.The effects of different reaction conditions on the trace oxygenates in the liquid products of co-cracking were discussed by comparing the results,LODs of six oxygenates were 0.14-0.30 mg/kg,and LOQs were 0.46-1.02mg/kg.The results showed that bio-oil water soluble phase/VGO could be successfully co-cracking in the pilot-scale riser.The increase of reaction temperature was beneficial to hydrogenation during co-cracking process,but the increase of thermal cracking resulted in the decrease of gasoline yield.The results of trace oxygenate analysis showed that the deoxidation capacity of catalytic cracking decreased with the increase of mixing ratio.The higher the reaction temperature,the stronger the deoxidation capacity of catalytic cracking.（5）Based on GC×GC-MS analysis platform,the quality control method of fatty acid methyl ester in bio-aviation fuel was established.The possible trace oxygenates in the liquid products of waste cooking oil hydrodeoxygenation process were simulated by mixing 6 FAME standard compounds（2 ppm,5 ppm）with bio aviation fuel.The results showed that at the spilt ratio of 10:1,LODs of six fatty acid methyl esters were 0.011-0.027 mg/kg,and LOQs were 0.036-0.090 mg/kg,and the GC×GC-MS research platform had the ability to detect FAME from 2 ppm to 5 ppm.On this basis,the bio aviation fuel product obtained from the catalytic hydrogenation of fatty acid methyl esters from waste cooking oil was analyzed by GC×GC-MS.The results showed that the liquid products obtained by hydrogenation at 400℃with Ni-Mo/γ-Al₂O₃&Meso-SAPO-11 as catalyst did not contain fatty acid methyl ester.