Conversion of Residual Biomass into Liquid Transportation Fuel: An Energy Analysis

An energy balance, in broad outline, is presented for the production of a high-quality liquid transportation fuel from residual crop biomass. The particular process considered is comprised of (1) harvesting surplus biomass (such as crop residue); (2) locally pyrolyzing the biomass into pyrolysis oil (PO), char, and noncondensable gas (NCG); (3) transporting the PO to a remote central processing facility; (4) converting the PO at this facility by autothermal reforming (ATR) into synthesis gas (CO and H₂); followed by, at the same facility, (5) Fischer–Tropsch (FT) synthesis of the syngas into diesel fuel. In carrying out our calculations, we have made several assumptions about the values of the process parameters. These parameters, of course, can be modified as better input data become available. The material and energy balance has been incorporated into an Excel spreadsheet. The scope and our approach to the energy budget using a widely available spreadsheet hopefully provides greater transparency, as well as ease of scenario manipulation than has generally been found in the literature. The estimated energy efficiencies computed with the spreadsheet are comparable to those obtained with Aspen software. A spreadsheet is offered as a tool for further analysis of the energy budget of this and related processes. The Excel spreadsheet can be used as a nimble scouting tool to indicate promising avenues of study in advance of using a more comprehensive analysis such as that afforded by Aspen software. The process considered, in which a portion of the char and noncondensable gas are used to supply heat to the drying and pyrolysis steps and under the assumptions made, was found to have an energy efficiency to liquid fuel on the order of 40%. That is, 40% of the initial energy in the biomass will be found in the final liquid fuel after subtracting out external energy supplied for complete processing, including transportation as well as material losses. If the energy of the remaining char and NCG is added to that in the product diesel oil, the total recovered energy is estimated to be ∼50% of the initial energy content of the biomass. If char and NCG are not used as a heat source in the process, the energy efficiency of the produced diesel drops from 40% to 15%. It must be realized that the distribution of energy content among the fast pyrolysis products PO, char, and NCG is ∼69%, ∼27%, and ∼4%, respectively. Therefore, using char and NCG to provide fuel for the drying and pyrolysis steps is very critical in maintaining high energy efficiency of the product fuel. The weight of diesel fuel produced is estimated to be ∼13% of the initial weight of biomass, implying that 1 t of biomass (30% moisture) will produce 1.0 barrels of diesel oil. The pyrolysis of biomass to PO, char, and NCG is estimated to have an intrinsic energy efficiency of ∼90%. For the model considered, trucking biomass to a central facility without first converting it to PO is estimated to reduce energy efficiency by ∼1%

Nickel phosphide catalyst for autothermal reforming of surrogate gasoline fuel

10.1002/aic.12505AIChE Journal57113143-3152AICE

High yield hydrogen from the pyrolysis-catalytic gasification of waste tyres with a nickel/dolomite catalyst

Nickel/dolomite catalysts have been prepared and investigated for their suitability for the production of hydrogen from the two-stage pyrolysis-gasification of waste tyres. Experiments were conducted at a pyrolysis temperature of 500 °C and gasification temperature was kept constant at 800 °C with a catalyst/waste tyres ratio of 0.5. Fresh and reacted catalysts were characterised using a variety of methods, including, BET, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM)-energy dispersive X-ray spectrometry (EDXS). The results indicated that the gas yield was significantly increased from 30.3 to 49.1 wt.% and the potential H production was doubled with the introduction of 5%Ni into the calcined dolomite catalyst. The results show also a further increase in the gas yield and the potential H production with increasing Ni loading from 5 to 20 wt.%. The coke deposited on the catalyst surface was 3.1, 0.9, 2.8 and 3.7 wt.%, when the Ni loading was 0, 5, 10 and 20 wt.% for the calcined dolomite catalyst, respectively. The results showed that the calcined Ni dolomite catalysts became deactivated by filamentous carbons

Comparison of waste plastics pyrolysis under nitrogen and carbon dioxide atmospheres: A thermogravimetric and kinetic study

It is important to understand the influence of pyrolysis atmosphere on the thermal degradation of waste plastics. In this study, the decomposition of waste plastics; high and low density polyethylene, polypropylene, polystyrene, and polyethylene terephthalate were investigated from ambient temperature to 500 °C within nitrogen or carbon dioxide atmospheres. The thermal degradation characteristics and kinetic parameters of individual plastics and mixed plastics (household packaging, building construction and agricultural waste plastics) from three different waste treatment plants were investigated under N2, CO2 and N2/CO2 atmospheres. In all atmospheres, only one degradation peak temperature was observed between 250−510 °C. The replacement of N2 by CO2 showed different effects on the activation energy. Mixtures of N2/CO2 in the pyrolysis atmosphere resulted to lower activation energy for all plastic samples, with the exception of high density polyethylene, polystyrene and polyethylene terephthalate. The lower activation energy suggested that lower energy was required for the degradation process. However, a mixture of more than 30 % of CO2 may influence the degradation process of plastics due to a higher value of residue obtained after the experiment