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37 results on '"Shafaghat, Hoda"'

10. Customized Atmospheric Catalytic Hydropyrolysis of Biomass to High-Quality Bio-Oil Suitable for Coprocessing in Refining Units

Author

Shafaghat, Hoda, Johansson, Ann-Christine, Wikberg, Elena, Narvesjö, Jimmy, Wagner, Jakob Birkedal, Öhrman, Olov, Shafaghat, Hoda, Johansson, Ann-Christine, Wikberg, Elena, Narvesjö, Jimmy, Wagner, Jakob Birkedal, and Öhrman, Olov

Abstract

This study aimed to investigate the critical elements of the biomass ex situ catalytic hydropyrolysis (CHP) concept to improve the quality of fast pyrolysis bio-oil (FPBO) for further coprocessing in a fluid catalytic cracking (FCC) refining unit. Generally, the high oxygen and low hydrogen contents of biomass result in a bio-oil with low quality, necessitating its upgrading, which can be performed as integrated in the pyrolysis process via in situ or ex situ configuration. In this work, the quality of stem wood-derived pyrolyzates (520 °C) was improved via ex situ CHP (400 °C) using a continuous bench-scale drop tube pyrolyzer (60 g h-1), and then the produced FPBO was coprocessed with vacuum gas oil (VGO) fossil oil using a lab-scale FCC unit (525 °C). CHP of stem wood was carried out using different metal-acid catalysts such as Ni/HZSM-5, Ni/HBeta, Mo/TiO2, and Pt/TiO2 at atmospheric pressure. FCC runs were performed using an equilibrium FCC catalyst and conventional fossil FCC feedstock cofed with 20 wt % stem wood-derived bio-oil in a fluidized bed reactor. Cofeeding the nonupgraded FPBO with fossil oil into the FCC unit decreased the generation of hydrocarbons in the range of gasoline and naphtha, indicating that bio-oil needs to be upgraded for further coprocessing in the FCC unit. Experimental results showed that different catalysts significantly affected the product composition and yield; Ni-based catalysts were strongly active tending to generate a high yield of gas, while Mo- and Pt-based catalysts seemed better for production of liquid with improved quality. The quality of FPBO was improved by reducing the formation of reactive oxygenates through the atmospheric CHP process. The composition of oil obtained from hydropyrolysis also showed that the yields of phenols and aromatic hydrocarbons were enhanced. © 2024 The Authors., The authors would like to thank the Swedish Energy Agency for financially supporting this study via the project P49685-1.

Published
2024
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26. Enhanced Biofuel Production via Catalytic Hydropyrolysis and Hydro-Coprocessing

Author

Shafaghat, Hoda, Linderberg, Mats, Janosik, Tomasz, Hedberg, Martin, Wiinikka, Henrik, Sandström, Linda, and Johansson, Ann-Christine

Abstract

In order to successfully integrate biomass pyrolysis oils as starting materials for conventional oil refineries, upgrading of the pyrolysis oils is needed to achieve desired properties, something which can be performed either as part of the pyrolysis process and/or by separate catalytic treatment of the pyrolysis intermediate oil products. In this study, the quality of stem wood-derived pyrolysis oil was improved via ex situ catalytic hydropyrolysis in a bench-scale pyrolyzer (stage 1), followed by catalytic hydro-coprocessing with fossil co-feed in a laboratory-scale high pressure autoclave (stage 2). The effect of pyrolysis upgrading conditions was investigated based on the quality of intermediate products and their suitability for hydro-coprocessing. HZSM-5 and Pt/TiO2catalysts (400 °C, atmospheric pressure) were employed for ex situ pyrolysis, and the NiMoS/Al2O3catalyst (330 °C, 100 bar H2initial pressure) was used for hydro-coprocessing of the pyrolysis oil. The application of HZSM-5 in the pyrolysis of stem wood under a N2atmosphere decreased the formation of acids, ketones, aldehydes, and furans and increased the production of aromatic hydrocarbons and phenolics (guaiacols and phenols). Replacing HZSM-5 with Pt/TiO2and N2with H2resulted in complete conversion of guaiacols and significant production of phenols, with further indications of increased stability and reduced coking tendencies.

Published
2022
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27. Catalytic hydrodeoxygenation and transfer hydrogenation of renewable ligninderived phenolics

Author

Shafaghat, Hoda, Rezaei, Pouya Sirous, and Daud, Wan Mohd Ashri Wan

Subjects
Lignin-derived phenolics, Upgrading, Pyrolysis oil, Hydrodeoxygenation, H-donor, SDG 7 - Affordable and Clean Energy, Reaction selectivity, Catalysis, Transfer hydrogenation
Abstract

Bio-oil obtained from biomass pyrolysis needs to be upgraded prior to its use as fuel since it contains high content of oxygenated compounds. Catalytic hydrodeoxygenation (HDO) is considered as an efficient technique for upgrading of pyrolysis bio-oil. The objective of this work was to study the HDO of phenolic compounds derived from lignin fraction of biomass since phenolics are highly stable in HDO reaction. Catalytic performance of Pd/C and Pt/C catalysts for HDO of renewable lignin-derived phenolic compounds (phenol, guaiacol and vanillin) and a simulated phenolic bio-oil was carried out at mild operating conditions of 275 °C and 16 bar hydrogen pressure. Pt/C showed to be more active than Pd/C for HDO of phenolic compounds. Meanwhile, physically mixed catalysts of HZSM-5 with Pt/C or Pd/C showed enhanced HDO efficiency compared to Pt/C and Pd/C due to promotion of reactions such as dehydration and hydrocracking over zeolite acid sites. Considering the difficult control of pressurized hydrogen gas in large industrial scale as well as high cost of molecular hydrogen production, it is of significant importance to find alternative sources of hydrogen. The feasibility of replacing hydrogen gas with liquid hydrogen donors was examined by transfer hydrogenation of the simulated phenolic bio-oil over Pt/C using decalin and tetralin as hydrogen source.

Published
2016

28. Ethanol production with natural carbon sources in batch and continuous fermentation using free and immobilized Saccharomyces cerevisiae

Author

Shafaghat, Hoda, Najafpour, Ghasem D., Rezaei, Pouya Sirous, and Sharifzadeh-Baei, Mazyar

Subjects
Ethanol production, Immobilized cells, Molasses, Kinetic parameters, Saccharomyces cerevisiae
Abstract

This study presents ethanol production from molasses, dates and sugarcane syrup with sugar concentration of 35g/l in batch culture. Molasses (retention time, 24 h; initial sugar concentration, 100 g/l) gave highest yield of ethanol [conc., 45.5 g/l (theoretical yield 89%)] in a packed bed reactor loaded with immobilized Saccharomyces cerevisiae beads (mean diam, 3 mm). After 16 h of cultivation, free cells were harvested for immobilization. Entrapment method was used to encapsulate free cells using 2.5% sodium alginate solution, solidified in calcium chloride bath. Growth kinetic model for S. cerevisiae in batch culture and rate model for performance of immobilized cell reactor (ICR) were determined.

Published
2011

37. OPTIMAL GROWTH OF Saccharomyces cerevisiae (PTCC 24860) ON PRETREATED MOLASSES FOR THE ETHANOL PRODUCTION: THE APPLICATION OF THE RESPONSE SURFACE METHODOLOGY.

Author

Shafaghat, Hoda, Najafpour, Ghasem D., Rezaei, Pouya Sirous, and Sharifzadeh, Mazyar

Subjects
*SACCHAROMYCES cerevisiae, *SUGAR beets, *MOLASSES, *FERMENTATION, *HYDROGEN-ion concentration, *YEAST extract, *ENZYMES
Abstract

Saccharomyces cerevisiae (PTCC 24860) growth on pretreated sugar beet molasses was an optimized via statistical approach. In order to liberate all monomeric sugars, pretreated sugar beet molasses with dilute acid was obtained. The influence of process parameters such as sugar concentration, nitrogen source, pH and incubation time on the cell growth were investigated by a design expert software with the application of a central composite design (CCD) under response surface methodology (RSM). The optimal culture conditions were pH of 5.3, incubation time of 24 h and medium composition of 35 g reduced sugars, 1.5 g NH4Cl and 1 g yeast extract per liter of the media. At optimal cell growth conditions and incubation time of 12 h, the maximum ethanol production of 14.87 g/L was obtained. [ABSTRACT FROM AUTHOR]

Published
2010
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