Papers by Manuel Garcia-perez
Chemsuschem, Nov 5, 2018
This is the author manuscript accepted for publication and has undergone full peer review but has... more This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.
Journal of Fundamentals of Renewable Energy and Applications, Sep 4, 2015
Energy technology, Sep 6, 2016
Formation of lignin oligomers from monomers Iowa State Group: Some oligomers in pyrolysis oil for... more Formation of lignin oligomers from monomers Iowa State Group: Some oligomers in pyrolysis oil form from the recombination of monomeric products! FORMATION OF OLIGOMERS According to Iowa State monomers are the main products of pyrolysis reactions. Oligomers are formed by thermochemical reactions. aromatic ring Clusters 2-5 aromatic rings Cluster 6> aromatic rings O Lignin Structure Lignin monomers O Lignin Oligomeric (liquid intermediate) Solid Residue (Char) Cross-linked lignin Low Temperature Reactions (180-300 o C) High Temperature Reactions (180-300 o C) Most of the literature considers that the lignin monomers are directly produced from the cracking of ether bonds in clusters with one aromatic ring OK OK OK OK OK Oligomers OK Under which conditions are they volatiles?
PLOS Water
Using biochar to remove phosphorus (P) from wastewater has the potential to improve surface water... more Using biochar to remove phosphorus (P) from wastewater has the potential to improve surface water quality and recycle recovered P as a fertilizer. In this research, effects of iron modification on P sorption behavior and molecular characterization on two different biochars and an activated carbon were studied. A biochar produced from cow manure anaerobic digest fibers (AD) pyrolyzed under NH3 gas had the greatest phosphate sorption capacity (2300 mg/kg), followed by the activated carbon (AC) (1500 mg/kg), and then the biochar produced from coniferous forest biomass (BN) (300 mg/kg). Modifying the biochars and AC with 2% iron by mass increased sorption capacities of the BN biochar to 2000 mg/kg and the AC to 2300 mg/kg, but decreased sorption capacity of the AD biochar to 1700 mg/kg. Molecular analysis of the biochars using P K-edge X-ray absorption near edge structure (XANES) spectroscopy indicated that calcium phosphate minerals were the predominant species in the unmodified biocha...
BioResources
A novel miniaturized, transparent reactor system for use as either a research or educational tool... more A novel miniaturized, transparent reactor system for use as either a research or educational tool was developed for investigating biomass char gasification with oxygen to determine the kinetic parameters. Parametric temperature and pressure data taken can be used to distinguish the validity of assumptions inherent in the Avrami, the random pore (RPM), the unreacted core shrinking (UCSM), and a UCSM hybrid models (HM). The results demonstrate the UCSM for spherical and cylindrical geometries, and an HM variation with a best-fit exponent, that yields residual sums of squares 2 to 4 orders of magnitude lower than other models. An Arrhenius evaluation yielded an activation energy of 84.8 kJ/mol and pre-exponential factor of 1.34 103 s-1. An O2 reaction order of 0.85 indicates O2 adsorption on the char surface is the primary rate-controlling step. Data are consistent with a rapidly decreasing surface area as the reaction nears completion, suggesting available corresponding active sites f...
Trends in green chemistry, Aug 9, 2017
With the growth of biomass processing in biorefineries, there is an increasing need to develop ra... more With the growth of biomass processing in biorefineries, there is an increasing need to develop rapid and simple methods for biomass characterization. One important component of biomass that is of signification interest in pyrolysis and liquefaction research is lignin, which is the world’s predominant source of renewable aromatic carbon. Due to its complex, heterogeneous nature and distinct variations among different biomass feedstocks, the characterization of lignins presents a unique challenge. In this study, we will show that clear divisions and comparisons can be made among a variety of lignins based on their FTIR spectra quantitatively assessed through principal component analysis (PCA). The eight lignins so far characterized are: two varieties of softwood kraft, one hardwood kraft, corn stover milled wood lignin (MWL), Douglas fir MWL, hybrid poplar MWL, wheat straw soda, and wheat straw organosolv. These samples were analyzed using a Bruker Alpha FTIR-ATR instrument (in additi...
Separating bio-oil by fractionation with different chemical compositions is a critical step to re... more Separating bio-oil by fractionation with different chemical compositions is a critical step to refine these oils and obtain high-value products. Cold water precipitation of pyrolytic lignin from bio-oil is the most common approach used. However, the obtained aqueous phase from this method still contains phenols and is diluted and difficult to use. In this study, the use of liquid− liquid extraction with different solvents (1-butanol, ethyl acetate, 1-octanol, dichloromethane, toluene, and hexane) for the separation of targeted molecules (lignin oligomers, sugars, acetic acid) is explored. Ternary phase diagrams for the organic solvent/ water/bio-oil are reported. The partition coefficient of compounds of interest (both light and heavy fractions) is reported for the liquid−liquid equilibrium zone. When using butanol as the solvent, the highest separation factor of total phenols over total sugars was observed. Our results provide information to design L−L separation units with the capacity to selectively recover targeted molecules from pyrolysis oils.
Journal of Food Science, 2019
Oak wood is used in barrels for wine aging. During aging, polyphenols are transferred from the ba... more Oak wood is used in barrels for wine aging. During aging, polyphenols are transferred from the barrels to the liquid. Although the bioactivity of oak polyphenols in wines has been extensively studied, no investigation exists on their toxicological properties, which limits their use as functional safe ingredients for other products. In this work, the chemical composition of a polyphenolic extract of Quercus crassifolia bark (QCBe) was studied by GC-MS. Its antibacterial properties on probiotic and pathogenic bacteria and its subacute-oral toxicity were determined as a way to understand the potential impact from its addition to fermented food as a functional ingredient. QCBe shows a selective inhibition of Escherichia coli compared with Lactobacillus bulgaricus and Streptococcus thermophylus. According to the toxicity evaluation, the subacute no-observed-adverse-effect-level was achieved at 11 mg/kg bw/day, whereas the subacute lowest-observedadverse-effect-level for kidney damage was at 33 mg/kg bw/day. These results suggest that, given the fact an adverse effect was observed after subacute administration of this extract, further longer term toxicological studies are needed to provide sufficient safety evidence for its use in humans.
Energy & Fuels, 2019
There is increasing interest in developing biobased alternative jet fuels to meet rising aviation... more There is increasing interest in developing biobased alternative jet fuels to meet rising aviation demand and address environmental concerns. Uncertainty of oil prices, issues of energy security, and rising greenhouse gas concentrations have spurred the development and acceptance of alternative, economically viable, environmentally sustainable production pathways. The objectives of this study were to review alternative jet fuel feedstock candidates and relevant conversion data to provide a baseline of information to be accessed and built upon in developing production scenarios in Hawai'i and other tropical regions bounded by the Tropic of Cancer in the northern hemisphere and the Tropic of Capricorn in the southern hemisphere. Seventeen plants that produce oil, fiber, and sugar feedstocks were identified, and information on cultural practices, yield ranges, invasiveness, and mechanization status was assembled. Available data on pretreatment requirements and conversion processes for the 17 feedstocks, including mass and energy balances, product and byproduct yield and quality, and scale requirements/unit sizes, were reviewed. This effort seeks to inform the development and design of alternative jet fuel production along regional supply chains in Hawai'i and other locations in the tropics.
Green Chemistry, 2019
Four principal intra-particle phenomena occur in a highly concerted manner during the pyrolysis o... more Four principal intra-particle phenomena occur in a highly concerted manner during the pyrolysis of lignocellulosic materials: heat transfer, mass transfer, chemical reactions, and phase changes.
Carbon, 2017
Recent results obtained by Raman spectroscopy as well as Transmission Electron Microscopy highlig... more Recent results obtained by Raman spectroscopy as well as Transmission Electron Microscopy highlight the importance of irregular structures within amorphous chars. Results from DFT simulations, reported here, suggest that irregular ring systems contribute strongly to the asymmetry often observed in the aromatic peak near 140 ppm. By combining a recently developed cross-polarization pulse sequence designed for quantitative analysis of even low hydrogen containing materials with long range dipolar dephasing, we examine the structure of a thermoseries of chars produced from cellulose. These results demonstrate the consistent growth of cluster size with pyrolysis temperature, and examine for the first time the distribution of ether groups and defects within the cluster. These results highlight the contribution of defects to the structure and show localization of ether groups toward the periphery of the clusters. Only minor ether contributions were associated carbon sites most distant from hydrogens, suggesting that cluster growth occurs largely by reaction at these sites. The prevalence of oxygenated and defect carbon sites throughout the aromatic clusters highlights the need for additional characterization of these materials as these sites are likely to offer substantially different reactivity and adsorption behavior compared to regular aromatic structures.
ACS Sustainable Chemistry & Engineering, 2018
Fatty acid and its derivatives have recently received considerable interest as a possible precurs... more Fatty acid and its derivatives have recently received considerable interest as a possible precursor for producing renewable hydrocarbon. Compared to the traditional hydrotreating method that consumes a significant amount of H2, this study developed a hydrothermal catalytic deoxygenation approach which produced hydrocarbon from fatty acids and bio-oil with in-situ self-sustaining H2. The presence of H2O played a critical role in the generation of in-situ H2 via enhancing water-gas shift and reforming reactions, thus promoted fatty acid decarbonylation and increased paraffin yields. Both saturated and unsaturated fatty acids (stearic and oleic acid) were employed as model compounds, where 100% conversion was achieved with 63.59% paraffin yield from stearic and 47% n-paraffin yield from oleic acid. By investigating the reaction pathway, fatty acid and glycerol reforming, and water-gas shift reactions were found as the major reactions for the in-situ H2 generation. Decarbonylation was found as the major route for fatty acid and bio-oil deoxygenation. Fatty acid reforming and hydrogenoloysis reactions were found as the major reactions for producing short-chain hydrocarbon (C8-C16). We previously developed a sequential hydrothermal liquefaction method to produce bio-oil from yeast biomass. In this study the produced bio-oil was also tested, where 100 wt% bio-oil conversion and 55.17 wt% of liquid n-paraffin yield were achieved at 320 °C. This study demonstrates that this hydrothermal catalytic process is a promising approach for producing liquid paraffin (C8-C15) from fatty acid and bio-oil under no H2 supply condition.
Reaction Chemistry & Engineering, 2016
The interplay of chemistry, heat and mass transfer at particle and reactor levels was studied for... more The interplay of chemistry, heat and mass transfer at particle and reactor levels was studied for the fast pyrolysis of cellulose.
Energy, 2017
Efficient conversion of all components in lignocellulosic biomass is essential to realizing econo... more Efficient conversion of all components in lignocellulosic biomass is essential to realizing economic feasibility of biorefineries. However, lignin cannot be fermented using biochemical routes. Furthermore, high lignin and high ash residues from simultaneous saccharification and fermentation (SSF) is difficult to thermochemically process due to feed line plugging and bed agglomeration. In this study a corn stover SSF digester residue was thermally pretreated at 300°C for 22.5 minutes and gasified in a fluidized bed gasifier to study the effect of thermal pretreatment on its processing behavior. Untreated, pelletized SSF residue was gasified at the same conditions to establish the baseline processing behavior. Results indicate the thermal pretreatment process removes a substantial portion of the polar and non-polar extractives, with a resultant increase in the concentration of lignin, cellulose, and ash. Feed line plugging was not observed, although bed agglomeration occurred at similar rates for both feedstocks, suggesting that overall ash content is the most important factor affecting bed agglomeration. Benzene, phenol, and polyaromatic hydrocarbons in the tar were present at higher concentrations in the treated material, with higher tar loading in the product gas. Total product gas generation is lower for the treated material, although overall gas composition does not change.
Innovative Solutions in Fluid-Particle Systems and Renewable Energy Management
The objective of this chapter is to review and discuss sustainability and techno-economic criteri... more The objective of this chapter is to review and discuss sustainability and techno-economic criteria to integrate pyrolysis, biochar activation, and bio-oil refining into sustainable business models. Several business models such as the production of biochar with heat recovery and bio-oil refining are discussed. Cost data needed by engineering practitioners to conduct enterprise-level financial analyses of different biomass pyrolysis economy models are presented. This chapter also reviews life cycle assessments of pyrolysis business models. If the feedstock used is produced sustainably and if the pyrolysis vapors are used for bio-oil or heat production, both, the production of biochar through slow pyrolysis and its use as a soil amendment to sequester carbon, and the production and refining of fast pyrolysis oils to produce transportation fuels could have a positive environmental impact.
Journal of Analytical and Applied Pyrolysis, 2014
Este documento contiene información de prueba. Contáctese con el administrador del Centro para el... more Este documento contiene información de prueba. Contáctese con el administrador del Centro para el acceso al documento originar del registro.
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Papers by Manuel Garcia-perez