Final Report Summary - BIOFUEL (Biofuels from Solid Wastes)
The aim of this project is the production of fuels from lignocellulosic biomass and waste plastics by pyrolysis and gasification.
Objectives:
1. Bio-oil production by pyrolysis of biomass and upgrading of bio-oil
2. Biofuel production by co-pyrolysis of biomass with waste plastics
3. Co-gasification of biomass with waste plastics
4. Gasification of biomass and the mixture of char+bio-oil from biomass pyrolysis.
RESULTS
The results were presented as four parts.
1. Pyrolysis of Biomass
An agricultural waste (safflower seed press cake-SC) and forest wastes (pine bark-PB, pine dust-PD and pine cone-PC) were pyrolyzed at different temperatures in presence and absence of catalyst in a “two-step pyrolysis” system. The commercial ReUS-Y (FCC catalyst), Red Mud (RM, a by-product from alumina production), and HZSM-5 were used as catalyst. The effect of temperature and catalyst on product yield and composition were investigated. Pyrolysis experiments carried out two step, which has a thermal fixed-bed reactor and a continuous catalytic reactor, and one-step pyrolysis systems, were carried out.
To avoid catalyst deactivation, two-step pyrolysis was found a potentially promising method. The temperature of 500 C was found to be optimum first step. This temperature produced highest liquid yield. The optimal temperatures of second step were also found to be as 500 °C (except fpr pine bark). The effect of catalyst varied depending on the biomass type. The catalysts used (especially ReUS-Y and HZSM-5) have an effect on the general composition of bio-oils, showing deoxygenation effect. Regarding to bio-oil yield, ReUS-Y catalyst was selected most suitable catalyst among the tested catalyst. Under optimum conditions, pyrolysis of biomasses produced the bio-oil with a yield of 8-19 wt %, gases (20-28 wt %), char (29-46 %) and an aqueous product ( 26-31 %). Aqueous phase consisted of mainly water (70-85 %) and water soluble organic compounds. The water soluble organic compounds are considered as valuable chemicals, their concentration is not high enough for their economic extraction. Although the catalysts used had effective on deoxygenation of bio-oil, the calorific value of oils is still lower than that of petroleum derived oils due to the higher oxygen content. It is important to point out that due to the high amount proteins in safflower oil cake the nitrogen content of bio-oils is higher than that of most of bio-oils derived from lignocellulosic biomasses. Pyrolysis of biomass produces a gas rich in carbon oxides due to the high oxygen content of feed material. Due to the high proportion of carbon oxides, pyrolysis gases have a low calorific value, but they can provide a part of the energy requirements for the pyrolysis plant. The chars were appropriate for household briquette production due to the low sulfur and high calorific value.
2. Co-pyrolysis of biomass with waste plastics
Co-pyrolysis of biomass with waste plastics is of interest both for commingled waste and also for relatively new commercial implemented products based on biocomposites. The recycling of composites is inherently difficult because of: their complex composition (fibres, matrix and fillers), the cross-linked nature of resins (which cannot be remoulded), and the combination with other materials, therefore pyrolysis is much feasible to apply to convert them in useful products. Copyrolysis was studied for of two groups of biomass, no studied until now namely woody biomass (eucalyptus globus and norway spruce) and biomass from annual plants (Brassica rape, energy grass (switchgrass), pine cones and grape seeds) in mixture with polypropylene in the ratio 30/70. Co-pyrolysis was performed by TG/FT-IR/DTA/MS coupled methods and pyrolysis in a glass reactor under self generated atmosphere. The characteristics of the volatile products were investigated. Differences in the pyrolysis behaviour among the composites containing various kind of biomass were found. Liquid products from pyrolysis of woody biomass give higher amount of carboxylic acids, ketones, and furans and lower amount of phenols than the biomass from annual plants. The distribution of compounds in oils is strongly depended on biomass source.
The other groups of studies were performed on poly(vinyl alcohol)/starch/montmorillonite nanocomposites used as bioartificial materials, chemically bonded composites, recyclable sizing agents and foamed blends or as disposable plates, cups, devices for transportation powdery materials and as biodegradable packaging materials. It has been established that the type and content of nanoclay (Nanocore I28, bentonite or Peruvian clay) influence both the pyrolysis pathway because the changes in the reaction mechanism and also the composition of the reaction products. The PVA/starch/clay nanocomposites shows completely different degradation product distribution patterns, which may be attributed to the presence of Si-O-C linkages formed between clay and blend components and also to formation of the head-to-head structures, new degradation products being formed. For example, the effect of the increase of the Nanocor I28 content consists mainly in a longer time of evolution start of the volatile compounds such as formic acid, water, formaldehyde, propionic acid, methanol, acetic acid carbon dioxide, benzene, etc.
Generally, the thermal behaviour of such polymeric nanocomposites containing montmorillonite is related to the organoclay content and its dispersion in matrix.
3. Co-gasification of biomass with waste plastics
Co-gasification in a two stage reactor of 70% PP/30% biomass composites was studied comparatively with those of components. As biomass in composites were selected: Eucalyptus globulus (EG), Brassica rapa (BR), Energy grass (EnG), Pine cones (PC). Both thermal and catalytic (in the presence of 10% Fe2O3/90%CeO2 catalyst) steam gasification was performed.
Catalytic gasification of PP occurs mainly in one decomposition step, before 500 ºC where high amount of H2 is produced. Gasification profiles of PP/biomass composites show the overlapping of the profiles of both component materials.
During steam gasification of the PP and biomass samples, CO, CO2, C1-C4 ligth hydrocarbons, and hydrogen were produced as gaseous products. Degradation of PP produces mainly H2, CH4, and C2-C4, while the biomass EG, BR, EnG and PC produces mainly H2, CO and CO2. The use of 10% Fe2O3/90%CeO2 catalyst in the steam gasification of plastic, biomass, and plastics/biomass composites resulted in the increase in production of gaseous products indicating that the catalyst accelerated the gasification rate. The amounts of hydrogen and CO2 increase at least two times after catalytic gasification as well as the CO amount in case of PP gasification, but the amount of CO decreases 3-4 times in the case of all biomasses and increases again for gasification of composites. Methane amount remains almost unchanged; in catalytic gasification in respect with thermal gasification for all samples. The light hydrocarbons C2-C4 remain almost similar for both kinds of gasification for all studied samples. Particularly the production of H2 and CO2 increased significantly which could be attributed to the effect of catalyst in water gas shift reaction of CO (CO + H2O → H2 + CO2). Also, it is obvious that hydrocarbons amount in biomass gas is much lower compare to plastics.
A synergistic effect of plastic and biomass during co-gasification was found which may be result from the interaction of the degradation products of the plastics and biomass.
Particularly, the production of H2 and CO2 increased significantly by 10% Fe2O3/90%CeO2 catalyst use.
4. Gasification of biomass and the mixture of char+bio-oil from biomass pyrolysis
The steam gasification of biomass and char/bio-oil was carried out using a down-flow dual-stage quartz microreactor under atmospheric pressure. Different biomasses (safflower seed cake-SC, walnut shale-WS, almond shell-AS, Eucalyptus globulus-EG, Brassica rapa-BR, Energy grass-EGr, and Pine cone-PC and the mixture of char+bio-oil from safflower seed cake pyrolysis were gasified under steam atmosphere in presence and absence of catalyst. The Iron oxide/Ceria with different ratios and Red Mud (RM, a by-product from alumina production) were used as catalyst. The effects of catalyst on gas composition and tar decomposition were investigated. The gasification experiments of bio-oil/charcoal slurry did not give the satisfy results. It was mentioned that the used experimental system, in which isothermal heating was used, was not useful for feedstock in slurry form.
In steam gasification of biomasses, the gases produced during the process were mainly H2, CO, CO2, CH4 and some higher hydrocarbons. Because of red-ox properties, the use of CeO2 as support improved the catalytic stability of iron based catalysts for tar degradation and hydrogen production.The highest H2 yield was obtained with 10%Fe2O3-90%CeO2. The highest hydrogen yields obtained were 1660cc/g biomass for AS, 1759cc/g biomass for WS, 1492 cc/g biomass for SC, 1085 cc /g biomass for EG, 1380 cc /g biomass for EGr, 1328 cc /g biomass for PC, 1382 cc /g biomass for BR.
CONCLUSION
Pyrolysis and gasification process proved to be suitable solution to obtain valuable products from various biomass wastes and also commingled waste containing both plastics and biomass as mixtures or composites and nanocomposites. Catalytic pyrolysis and gasification increase the yield in desired products, upgraded them and decrease energetic consumption.
Objectives:
1. Bio-oil production by pyrolysis of biomass and upgrading of bio-oil
2. Biofuel production by co-pyrolysis of biomass with waste plastics
3. Co-gasification of biomass with waste plastics
4. Gasification of biomass and the mixture of char+bio-oil from biomass pyrolysis.
RESULTS
The results were presented as four parts.
1. Pyrolysis of Biomass
An agricultural waste (safflower seed press cake-SC) and forest wastes (pine bark-PB, pine dust-PD and pine cone-PC) were pyrolyzed at different temperatures in presence and absence of catalyst in a “two-step pyrolysis” system. The commercial ReUS-Y (FCC catalyst), Red Mud (RM, a by-product from alumina production), and HZSM-5 were used as catalyst. The effect of temperature and catalyst on product yield and composition were investigated. Pyrolysis experiments carried out two step, which has a thermal fixed-bed reactor and a continuous catalytic reactor, and one-step pyrolysis systems, were carried out.
To avoid catalyst deactivation, two-step pyrolysis was found a potentially promising method. The temperature of 500 C was found to be optimum first step. This temperature produced highest liquid yield. The optimal temperatures of second step were also found to be as 500 °C (except fpr pine bark). The effect of catalyst varied depending on the biomass type. The catalysts used (especially ReUS-Y and HZSM-5) have an effect on the general composition of bio-oils, showing deoxygenation effect. Regarding to bio-oil yield, ReUS-Y catalyst was selected most suitable catalyst among the tested catalyst. Under optimum conditions, pyrolysis of biomasses produced the bio-oil with a yield of 8-19 wt %, gases (20-28 wt %), char (29-46 %) and an aqueous product ( 26-31 %). Aqueous phase consisted of mainly water (70-85 %) and water soluble organic compounds. The water soluble organic compounds are considered as valuable chemicals, their concentration is not high enough for their economic extraction. Although the catalysts used had effective on deoxygenation of bio-oil, the calorific value of oils is still lower than that of petroleum derived oils due to the higher oxygen content. It is important to point out that due to the high amount proteins in safflower oil cake the nitrogen content of bio-oils is higher than that of most of bio-oils derived from lignocellulosic biomasses. Pyrolysis of biomass produces a gas rich in carbon oxides due to the high oxygen content of feed material. Due to the high proportion of carbon oxides, pyrolysis gases have a low calorific value, but they can provide a part of the energy requirements for the pyrolysis plant. The chars were appropriate for household briquette production due to the low sulfur and high calorific value.
2. Co-pyrolysis of biomass with waste plastics
Co-pyrolysis of biomass with waste plastics is of interest both for commingled waste and also for relatively new commercial implemented products based on biocomposites. The recycling of composites is inherently difficult because of: their complex composition (fibres, matrix and fillers), the cross-linked nature of resins (which cannot be remoulded), and the combination with other materials, therefore pyrolysis is much feasible to apply to convert them in useful products. Copyrolysis was studied for of two groups of biomass, no studied until now namely woody biomass (eucalyptus globus and norway spruce) and biomass from annual plants (Brassica rape, energy grass (switchgrass), pine cones and grape seeds) in mixture with polypropylene in the ratio 30/70. Co-pyrolysis was performed by TG/FT-IR/DTA/MS coupled methods and pyrolysis in a glass reactor under self generated atmosphere. The characteristics of the volatile products were investigated. Differences in the pyrolysis behaviour among the composites containing various kind of biomass were found. Liquid products from pyrolysis of woody biomass give higher amount of carboxylic acids, ketones, and furans and lower amount of phenols than the biomass from annual plants. The distribution of compounds in oils is strongly depended on biomass source.
The other groups of studies were performed on poly(vinyl alcohol)/starch/montmorillonite nanocomposites used as bioartificial materials, chemically bonded composites, recyclable sizing agents and foamed blends or as disposable plates, cups, devices for transportation powdery materials and as biodegradable packaging materials. It has been established that the type and content of nanoclay (Nanocore I28, bentonite or Peruvian clay) influence both the pyrolysis pathway because the changes in the reaction mechanism and also the composition of the reaction products. The PVA/starch/clay nanocomposites shows completely different degradation product distribution patterns, which may be attributed to the presence of Si-O-C linkages formed between clay and blend components and also to formation of the head-to-head structures, new degradation products being formed. For example, the effect of the increase of the Nanocor I28 content consists mainly in a longer time of evolution start of the volatile compounds such as formic acid, water, formaldehyde, propionic acid, methanol, acetic acid carbon dioxide, benzene, etc.
Generally, the thermal behaviour of such polymeric nanocomposites containing montmorillonite is related to the organoclay content and its dispersion in matrix.
3. Co-gasification of biomass with waste plastics
Co-gasification in a two stage reactor of 70% PP/30% biomass composites was studied comparatively with those of components. As biomass in composites were selected: Eucalyptus globulus (EG), Brassica rapa (BR), Energy grass (EnG), Pine cones (PC). Both thermal and catalytic (in the presence of 10% Fe2O3/90%CeO2 catalyst) steam gasification was performed.
Catalytic gasification of PP occurs mainly in one decomposition step, before 500 ºC where high amount of H2 is produced. Gasification profiles of PP/biomass composites show the overlapping of the profiles of both component materials.
During steam gasification of the PP and biomass samples, CO, CO2, C1-C4 ligth hydrocarbons, and hydrogen were produced as gaseous products. Degradation of PP produces mainly H2, CH4, and C2-C4, while the biomass EG, BR, EnG and PC produces mainly H2, CO and CO2. The use of 10% Fe2O3/90%CeO2 catalyst in the steam gasification of plastic, biomass, and plastics/biomass composites resulted in the increase in production of gaseous products indicating that the catalyst accelerated the gasification rate. The amounts of hydrogen and CO2 increase at least two times after catalytic gasification as well as the CO amount in case of PP gasification, but the amount of CO decreases 3-4 times in the case of all biomasses and increases again for gasification of composites. Methane amount remains almost unchanged; in catalytic gasification in respect with thermal gasification for all samples. The light hydrocarbons C2-C4 remain almost similar for both kinds of gasification for all studied samples. Particularly the production of H2 and CO2 increased significantly which could be attributed to the effect of catalyst in water gas shift reaction of CO (CO + H2O → H2 + CO2). Also, it is obvious that hydrocarbons amount in biomass gas is much lower compare to plastics.
A synergistic effect of plastic and biomass during co-gasification was found which may be result from the interaction of the degradation products of the plastics and biomass.
Particularly, the production of H2 and CO2 increased significantly by 10% Fe2O3/90%CeO2 catalyst use.
4. Gasification of biomass and the mixture of char+bio-oil from biomass pyrolysis
The steam gasification of biomass and char/bio-oil was carried out using a down-flow dual-stage quartz microreactor under atmospheric pressure. Different biomasses (safflower seed cake-SC, walnut shale-WS, almond shell-AS, Eucalyptus globulus-EG, Brassica rapa-BR, Energy grass-EGr, and Pine cone-PC and the mixture of char+bio-oil from safflower seed cake pyrolysis were gasified under steam atmosphere in presence and absence of catalyst. The Iron oxide/Ceria with different ratios and Red Mud (RM, a by-product from alumina production) were used as catalyst. The effects of catalyst on gas composition and tar decomposition were investigated. The gasification experiments of bio-oil/charcoal slurry did not give the satisfy results. It was mentioned that the used experimental system, in which isothermal heating was used, was not useful for feedstock in slurry form.
In steam gasification of biomasses, the gases produced during the process were mainly H2, CO, CO2, CH4 and some higher hydrocarbons. Because of red-ox properties, the use of CeO2 as support improved the catalytic stability of iron based catalysts for tar degradation and hydrogen production.The highest H2 yield was obtained with 10%Fe2O3-90%CeO2. The highest hydrogen yields obtained were 1660cc/g biomass for AS, 1759cc/g biomass for WS, 1492 cc/g biomass for SC, 1085 cc /g biomass for EG, 1380 cc /g biomass for EGr, 1328 cc /g biomass for PC, 1382 cc /g biomass for BR.
CONCLUSION
Pyrolysis and gasification process proved to be suitable solution to obtain valuable products from various biomass wastes and also commingled waste containing both plastics and biomass as mixtures or composites and nanocomposites. Catalytic pyrolysis and gasification increase the yield in desired products, upgraded them and decrease energetic consumption.