Ofei D. Mante

The influence of recycling non-condensable gases in the fractional catalytic pyrolysis of biomass

In this study, the effect of recycling the non-condensable gases (NCG) in the catalytic pyrolysis of hybrid poplar using FCC catalyst was investigated. A 50mm bench scale fluidized bed reactor at 475°C with a weight hourly space velocity (WHSV) of 2h(-1) and a gas recycling capability was used for the studies. Model fluidizing gas mixtures of CO/N(2), CO(2)/N(2), CO/CO(2)/N(2) and H(2)/N(2) were used to determine their independent effects. Recycling of the NCG in the process was found to potentially increase the liquid yield and decrease char/coke yield. The model fluidizing gases increased the liquid yield and the CO(2)/N(2) fluidizing gas had the lowest char/coke yield. The (13)C-NMR analysis showed that recycling of NCG increases the aromatic fractions and decreases the methoxy, carboxylic and sugar fractions. Recycling of NCG increased the higher heating value and the pH of the bio-oil as well as decreased the viscosity and density.

Storage stability of biocrude oils from fast pyrolysis of poultry litter.

The unstable nature of biocrude oils produced from conventional pyrolysis of biomass is one of the properties that limits its application. In the disposal of poultry litter via pyrolysis technology, the biocrude oil produced as a value-added product can be used for on farm applications. In this study, we investigated the influence of bedding material (wood shavings) on the storage stability of biocrude oils produced from the fast pyrolysis of poultry litter. The biocrude oils produced from manure, wood (pine and oak), and mixtures of manure and wood in proportions (75:25 50:50, and 25:75w/w%) were stored under ambient conditions in sealed glass vials for a period of 6 months and their stability were monitored by measuring the changes in viscosity over time. The manure oil had the lowest rate of viscosity change and thus was relatively the most stable and the oils from the 50:50w/w% litter mixtures were the least stable. The rate of viscosity change of the manure biocrude oil was 1.33cP/day and that of the 50/50 litter mixture was 7.6cP/day for pine and 4.17cP/day for oak. The spectrometric analyses of the biocrude oils showed that the presence of highly reactive oxygenated functionalities in the oil were responsible for the instability characteristic of the litter biocrude oils. The poor stability of the biocrude oil from the 50:50w/w% litter mixtures was attributed to reactions between nitrogenous compounds (amides) from protein degradation and oxygenated compounds from the decomposition of polysaccharides and lignin. The addition of 10% methanol and 10% ethanol to the oil from 50% manure and 50% pine reduced the initial viscosity of the oil and was also beneficial in slowing down the rate of viscosity change during storage.

Catalytic pyrolysis for the production of refinery-ready biocrude oils from six different biomass sources

This study focused on understanding the impact of catalytic pyrolysis and biomass feedstock on the physicochemical properties of upgraded bio-oils. Results from catalytic conversion of different types of biomass feedstocks (woody: pine, hybrid poplar and pinyon-juniper; herbaceous: switchgrass; agricultural residue: corn stover; and forest residue: pine bark) with HZSM-5 zeolite to biocrude oils are presented. The study showed that the source of biomass plays an important role in catalytic pyrolysis products. Significant differences were observed in product distribution, selectivity to aromatic hydrocarbons and physicochemical properties of the biocrude oils. The pyroprobe-GC/MS experiment showed that pine and pinyon-juniper produced the highest carbon yield of monoaromatic hydrocarbons. 13C NMR analysis revealed that aromatic hydrocarbon content of the oils followed this order: pinyon-juniper > corn stover > pine > poplar > switchgrass > pine bark. The chemical composition and the physicochemical properties indicated that it is critical to reduce carbonyls to achieve stable oils. Also, it was found that elimination of sugars (levoglucosan) and phenolics would improve oil specific gravity and viscosity. Furthermore, reducing the acidity of oils by catalytic pyrolysis appeared to be very challenging. Hence, phenols (weak acids) may have to be minimized in addition to other acids to increase the pH. The nitrogen contents correlated with pH values. Thus, feedstocks with high nitrogen content produced less acidic oils. Nonetheless, high content of nitrogenous compounds could make the biocrude oil highly unstable. The effects of the bio-oil chemical composition on the physicochemical properties are discussed as well as opportunities and challenges of utilizing biocrude oil as feed for standard refinery units.

Influence of pine wood shavings on the pyrolysis of poultry litter.

Poultry litter from broilers and turkeys are a mixture of manure, feathers, feed and wood shavings, thus pyrolysis oils produced from this material are influenced by the individual components. In order to determine the influence of wood shavings that are used as bedding material, we investigated the pyrolysis of pine wood shavings and poultry manure. Because manure from layer chickens are usually not contaminated with wood shavings, we made mixtures of layer manure and pine wood shavings in the following manure to wood ratios, 100:0, 75:25, 50:50, 25:75, and 0:100 w/w and pyrolyzed them in a fluidized bed reactor at 450 °C. The total liquid yield ranged from 43.3 to 62.7 wt.%. The layer manure oil had a HHV of 29.7 MJ/kg and pH of 5.89 compared to pine wood oil which had HHV of 25.6 MJ/kg and pH of 3.04. The addition of wood shavings to manure clearly influenced the physical properties of the oil, resulting in a decrease in pH and HHV and an increase in density. The oils had relatively high nitrogen content ranging from 1.36 to 5.88 wt.%. The ash (<0.07 wt.%) and sulfur (<0.28 wt.%) contents were very low. FTIR, (13)C NMR and (1)H NMR spectrometric analysis of the oils showed that manure oil was rich in hydrocarbons and nitrogenous compounds such as primary, secondary amides, aromatic amines and N-heterocyclic. The properties of the oils were strongly influenced by the amount of wood in the mixture.

Catalytic conversion of biomass pyrolysis vapors into hydrocarbon fuel precursors

We report on a new pyrolytic pathway for biomass conversion to hydrocarbon fuel precursors. The process entails the conversion of multifunctional oxygenates generated from biomass pyrolysis over a metal oxide catalyst into ketonic-rich monofunctional molecules suitable for making hydrocarbon fuel components for gasoline, diesel, and jet fuel. A number of catalysts were explored, for example, anatase TiO2 nanorods, CeOx–TiO2 mixed oxides, pure CeO2, ZrO2, and MgO. Under pyrolysis conditions, ceria-based catalysts were effective in the conversion of hydroxy-carbonyls, anhydrosugars, and carboxylic acids into acetone, 2-butanone, pentanones, C6/C7 ketones, cyclopentanone, and 2-cyclopentenones. The highest carbon yield (23.5%) of ketonic precursors was achieved on the pure CeO2.

Selective defunctionalization by TiO2 of monomeric phenolics from lignin pyrolysis into simple phenols.

This study is focused on defunctionalizing monomeric phenolics from lignin into simple phenols for applications such as phenol/formaldehyde resins, epoxidized novolacs, adhesives and binders. Towards this goal, Titanium dioxide (TiO2) was used to selectively remove hydroxyl, methoxy, carbonyl and carboxyl functionalities from the monomeric phenolic compounds from lignin to produce mainly phenol, cresols and xylenols. The results showed that anatase TiO2 was more selective and active compared to rutile TiO2. Catechols were found to be the most reactive phenolics and 4-ethylguaiacol the least reactive with anatase TiO2. An overall conversion of about 87% of the phenolics was achieved at 550°C with a catalyst-to-feed ratio of 5 w/w. Over 97% conversion of phenolics is achievable at moderate temperatures (550°C or ≤ 600°C) and a moderate catalyst-to-feed ratio of 6.5:1. The reactivity of catechols on TiO2 suggests that titania is a promising catalyst in the removal of hydroxyl moiety.