Feedstock Ratio Research Articles

Optimal blending under general uncertainties: A chance-constrained programming approach

An optimization algorithm is proposed for blend planning with linear mixing law and general parameter uncertainties. The objective is to make the final product satisfy all quality specifications with high probability, and maximize the production profit by carefully determining the feedstock ratio. Conventional approaches that rely on deterministic optimization fail to account for parameter uncertainty, and thus may not generate a probabilistic feasible solution. The proposed work formulates the blend planning problem as a joint chance-constrained program (CCP). Using Boole’s inequality to decompose joint constraints and the Gaussian mixture model to characterize uncertainty distributions, a conservative deterministic approximation of CCP can be formulated. Through second-order cone relaxation, branch-and-bound, optimality-based bound tightening, and reformulate-linearization techniques, the global optimum of deterministic approximation can be found. A risk level adjustment procedure is presented to reduce the conservativeness and further improve the objective value of the solution if posterior evaluation is allowed. Two numerical cases, including steel and gasoline productions, are studied to show the solving time, probabilistic feasibility, and solution quality of the proposed optimization method.

Transforming micropores to mesopores by heat cycling KOH activated petcoke for improved kinetics of adsorption of naphthenic acids

Formation of activated carbon from petroleum coke by KOH, results in high specific surface area materials that are predominantly microporous. This initial microporosity means that the adsorption kinetics of target species are not as rapid as they could be, thus limiting environmental remediation applications for the material. To address this problem a series of additional heat cycles with no additional chemical inputs were applied after activation but prior to the removal of activating agents. This process resulted in the oxidation of residual potassium metal from the initial activation which allows it to function again as an activating agent for the subsequent cycles. The heat cycling resulted in an increase in mesoporosity by 10–25% with each successive cycle independent of the KOH to feedstock ratio. This was shown to be demonstrably different than equivalently extended heating times, thus identifying the importance of thermal cycling. Adsorption kinetics of three model naphthenic acids showed faster kinetics for the pore widened activated carbon. The t1/2 times dropped from 20 to 6.6 min for diphenyl acetic acid, 34.3 to 4.5 min for cyclohexane acetic acid, and 51.4 to 12.0 min for heptanoic acid.

Thermodynamics of Hydrogen Storage: Equilibrium Study of Liquid Organic Hydrogen Carrier System 1-Methylindole/octahydro-1-methylindole

Methylated indoles could be potentially interesting components for hydrogen (H2) storage based on the Liquid Organic Hydrogen Carrier (LOHC) approach. It is likely that the methylated forms will preserve the beneficial thermochemical characteristics of indole compared to homocyclic LOHCs. At the same time, 1-methyl-indole is expected to have a higher stability than indole in the reactive cycle of hydrogenation and dehydrogenation. This study investigates whether the expectations regarding reaction thermodynamics and stability are justified. To this end, the chemical equilibria of the hydrogenation (+H2)/dehydrogenation (−H2) reactions of the indole/octahydroindole LOHC system was determined experimentally over a wide range of temperature, pressure, and hydrogen:feedstock ratio. Reaction thermodynamics were calculated from the relationship between temperature and equilibrium constant. In addition, the formation enthalpies of the species involved in the reaction have been determined experimentally utilizing combustion calorimetry. Further validation has been achieved using high-level quantum chemical methods. The evaluation confirms both hypotheses: (1) 1-methyl-indole exhibits less decomposition during reaction as is the case for the indole system. Hence, an improved stability of methylated LOHC molecules can be concluded; (2) The enthalpy of reaction for H2 release from octahydro-1-methyl-indole is estimated from the equilibrium experiments and calorimetric measurements to be about +55.6 kJ mol(H2)−1 for reaction in the liquid phase at standard conditions. This is comparable to the values observed for octahydro-indole.

Comparative study of manganese oxides with different oxidation states for catalytic carbonylation of n-butylamine by CO2

The four manganese oxides with different oxidation states (MnO, MnO2, Mn2O3, Mn3O4) was synthesized using the hydrothermal method through adjusting process parameters and feedstock ratio, and their catalytic performances for the carbonylation of n-butylamine by CO2 were also investigated. The results showed that the catalytic activities of manganese oxides with different oxidation states in the catalytic carbonylation of n-butylamine by CO2 follow the order of MnO2 > Mn3O4 > Mn2O3 > MnO, in which MnO2 with the Mn4+ ion exhibited as high as 91.60% yield of N,N'-dibutylurea using polyethylene glycol 400 (PEG 400) as solvent under the reaction conditions of 160 ℃, 4 h, and 5.0 MPa. And then a series of characterization including XRD, XPS, H2-TPR, and CO2/NH3-TPD were performed on the as-synthesized manganese oxides with different oxidation states, indicating that the content of oxygen vacancy on the surface of the manganese oxides with different oxidation states plays a key role in catalytic performances of the carbonylation of n-butylamine with CO2.

The Cultivation of Water Hyacinth in India as a Feedstock for Anaerobic Digestion: Development of a Predictive Model for Scaling Integrated Systems

A novel, integrated system is proposed for the cultivation and co-digestion of the invasive macrophyte water hyacinth (WH) with cow manure (CM) for the production of biogas for cooking in rural India. This study investigates the pre-treatment approaches and performs a techno-economic analysis of producing biogas in fixeddome digesters as a replacement for liquefied petroleum gas (LPG). Methodologies have been developed for the cultivation of WH collected from wild plants in the Indrayani River, Pune, India. Cultivation trials were performed in 350 litre tanks using water, which was nutrient fed with CM. Cultivation trials were performed over a 3 week period, and growth rates were determined by removing and weighing the biomass at regular time intervals. Cultivation results provided typical yields and growth rates of biomass, allowing predictions to be made for cultivation scaling. Samples of cultivated WH have been co-digested with CM at a 20:80 ratio in 200 L anaerobic digesters, allowing for the prediction of bio-methane yields from fixed-dome anaerobic digesters in real world conditions, which are commonly used in the rural locations of India. A calculator has been developed, allowing us to estimate the scaling requirements for the operation of an integrated biomass cultivation and anaerobic co-digestion unit to produce an equivalent amount of biogas to replace between one and three LPG cylinders per month. A techno-economic analysis of introducing WH into fixed-dome digesters in India demonstrated that the payback periods range from 9 years to under 1 year depending on the economic strategies. To replace between one and three LPG cylinders per month using the discussed feedstock ratio, the cultivation area of WH required to produce sufficient co-feedstock ranges within 10–55 m2.

Thermodynamics of hydrogen storage: Equilibrium study of the LOHC system indole/octahydroindole

Reversible hydrogenation of indole or its derivatives could be an attractive hydrogen storage technology. Particularly for hydrogen release, the reaction equilibrium is a crucial factor determining the conditions in the respective process. This study is supposed to provide inside into this reaction equilibrium. An experimental study of the chemical equilibrium of hydrogenation/dehydrogenation reactions was performed in a stirred autoclave with n–hexane as a solvent by varying the temperature, pressure, and hydrogen:feedstock ratio. Based on the compositions in stationary state, equilibrium constants have been derived. Furthermore, thermodynamic properties of chemical reactions were derived from the equilibrium constant temperature dependence. This temperature dependence reveals that the enthalpy of reaction for the dehydrogenation of the six-membered ring is significantly larger than in the nitrogen containing five-membered ring. To get deeper insides, the molar enthalpies of formation of intermediates have been calculated using high-level quantum chemical methods. This analysis supports the observations from the equilibrium reactions. Additionally, it show that the heat of reaction for the endothermal dehydrogenation is about 2 kJ mol (H2)–1 smaller in the liquid phase than in case of a gas phase reaction.

Trial of Biopellet Prepared by Napier Grass.

Pelletization from nonwoody biomass has gained a lot of attention due to its potential to secure biomass feedstock supply and pricing. Studies have been conducted to produce biopellets from different parts of Napier grass plant. In this study, two different species of Napier grass were used. Two pressure points and five different times were varied accordingly. Proximate, ultimate, and Fourier transform infrared spectroscopy (FTIR) analyses were performed to assess chemical properties. Statistical analysis of the collected data validated and supported the discussion. The produced pellets of Napier grass exhibited good energy density comparable to those in the literature based on gross calorific values. The pellet density demonstrated a significant effect with time, pressure, and feedstock ratios. The pellet durability test showed comparable characteristics to another biomass pellet. Both Pakchong Napier grass (PNG) and wild Napier grass (WNG) biopellet densities obtained were higher than 0.650 g/cm3, and the durability was higher than 95%. This signifies that the pellet can withstand repeated transfer during handling without breakage.

Technical, Environmental, and Process Safety Assessment of Acetone-Butanol-Ethanol Fermentation of Cassava Residues

The North-Colombian region has enormous potential for producing bioproducts and bioenergy from agricultural residues. Yet, scaling bioproducts and bioenergy to industrial practice requires further investigation, especially for environmental impact minimization and improved process safety. This work assesses two alternatives for valorizing cassava residues via acetone, butanol, and ethanol (ABE) fermentation. Two ABE fermentation routes are assessed. In Route 1, pretreatment and purification involve dilute-acid pretreatment and multi-effect distillation and decantation operations, while Route 2 includes steam explosion and reactive distillation. Hazard Identification and Risk Assessment (HIRA) and Waste Reduction Algorithm (WAR) were applied to assess ABE fermentation. Simulation results indicate butanol yields of 0.10–0.12 kg/kg feedstock and net energy ratio (NER) <1. Route 2 shows the highest total output of Potential Environmental Impacts (PEI) with 5.56 PEI/kg butanol. Both ABE fermentation routes obtained Fire and Explosion Damage Index (FEDI) values above 300 for acetone and ethanol recovery/purification stages. Both routes are classified as “hazardous” considering the flammability of handled substances, and their relative safety performance is remarkably similar. These results pave the way toward deploying both routes for adding value to the cassava residues in North Colombia by applying safe, efficient, and environmentally friendly transformation technologies.

Microwave pyrolyzed sewage sludge: influence on soil microbiology, nutrient status, and plant biomass

BackgroundSewage sludge (SS) has been considered a potent source of soil nutrients. However, its direct application to agricultural soils have been discouraged owing to its toxic nature. Therefore, conversion and modification of SS to decrease its toxicity has resulted in advanced methods. Co-pyrolysis of SS with other amendments is an ideal treatment resulting in an environmentally safe and nutrient rich final products with additional properties to sequester carbon. In the present study, a novel biochar was produced through the microwave pyrolysis of SS mixed with zeolite and sawdust. The pyrolysis product was thus characterized for elemental composition, polycyclic aromatic hydrocarbons, via Fourier Transform Infrared Spectroscopy (FTIR), and for its effects on soil microbial characteristics, soil health and plant biomass after soil application.ResultsResults revealed that, the SS modification resulted in stable product with higher nutrients which further depend on the type and ratio of feedstock used. Its application to soil significantly improved soil chemical and microbiological properties and altered lettuce biomass.ConclusionsWe concluded that sawdust feedstock promoted nutrient availability in the resulting biochar and induced higher activity of nutrient mineralizing enzymes, whereas zeolite slowed down the release of nutrients from soil and putatively immobilized enzymes. This joint effect of sewage sludge biochar, sawdust and zeolite benefited the plant acquisition of nutrients in comparison with the microbial nutrient uptake. We thus conclude that microwave pyrolyzed SS could be used as a soil enhancer.Graphical

Facile Catalyst‐Free Approach toward Fully Biobased Reprocessable Lignin Thermosets

AbstractReprocessable and biobased thermosets are prepared from two renewable feedstocks, lignin and polyamine (Priamine 1071). Lignin is oxidized to produce polycarbonyl and further reacts with polyamine to form a crosslinked network of imines. The thermoset materials are formed under heat and pressure in the absence of any catalysts. The mechanical strength and thermal properties of thermosets are tunable by changing feedstock ratios. The dynamic imine crosslinks can be associatively reformed.

Catalytic fast pyrolysis of herbal medicine wastes over zeolite catalyst for aromatic hydrocarbons production

Catalytic pyrolysis is an effective method to upgrade biomass pyrolytic bio-oil. In this study, catalytic fast pyrolysis (CFP) of licorice residue (LR) over ZSM-5 was conducted using pyrolysis–gas chromatography/mass spectrometry. The effects of temperature, Si/Al atomic ratio (SAR) and catalyst to feedstock (C/F) ratio on the formation of aromatic hydrocarbons (AHs) were investigated. The results indicated that ZSM-5 effectively converts oxygenates into AHs. Specifically, benzene, toluene, ethylbenzene, p-xylene and naphthalene (BTEXN) were the dominant components. The pyrolysis temperature and acidity of zeolite exert a greater influence on the formation of BTEXN. The maximum content of BTEXN was 73.45 % at 500 °C and 72.21 % at lower SARs (27 and 36). Coke can be formed and deposited on the zeolite during CFP of LR, which cause the deactivation of catalyst. A higher pyrolysis temperature and C/F ratios inhibits the coke formation, while a higher SAR is beneficial to coke formation. The large oxygenated molecules and aliphatic hydrocarbons (AHCs) was the precursors of coke during catalytic pyrolysis. The coke was tended to disperse on the surface of catalyst at low temperature. However, it was largely deposited in the channels of zeolite catalyst at high temperatures. This study reveals that ZSM-5 is an effective catalyst for the utilization of herbal medicine wastes. The pyrolytic bio-oil has high potential for use in fuels or renewable chemical production.

Sawdust biomass promotes aquathermolysis of extra-heavy oil

The application of biomass to the enhanced oil recovery of extra-heavy oil is a promising technology. In this paper, the promoting effect of sawdust on the viscosity reduction of extra-heavy oil was discussed. During the experiment, sawdust and extra-heavy oil were co-aquathermolysis. The experimental results showed that the viscosity of extra-heavy oil can be reduced from 145 Pa·s to 10.42 Pa·s at 553 K for 24 h and the feedstock ratio of sawdust: extra-heavy oil: water is 1:50:50. Elemental analysis of extra-heavy oil showed that the H/C increased from 1.4347 to 1.6296, and the oxygen content increased from 2.05 wt% to 5.61 wt%. Compared with the upgrading oil without sawdust, the viscosity decreased by 11.03 Pa·s and the H/C increased by 0.0832. The GC–MS results show that the dehydrogenation and deoxidation reactions of small molecular substances generated by sawdust provide hydrogen and oxygen sources for the upgrading of extra-heavy oil.

Biodrying with the hot-air aeration system for kitchen food waste.

Biodrying is a promising method that produces bio-stabilized output with minimum pretreatment requirements. In this study, a hot-air supply system was added to the traditional biodrying process for kitchen waste, which showed significant reduction in moisture content in 5 days (maximum reduction of 37.45%). A series of experiments was conducted to optimize the hot-air biodrying system utilizing different aeration rates, temperatures, and mixing ratios of feedstock to bulking agents. The results showed that a 65°C aeration temperature led to the highest water removal rate and low volatile solids consumption rate, with the biodrying index reaching 4.9g water per gram of volatile solids. On the other hand, evaluation of the overall biodrying efficiency based on the weight loss and bio-stabilization showed that intermittent aeration temperature at 55°C performed best, offering suitable conditions for water evaporation and bio-degradation. In combination with a flow rate of 0.8L/kg*min and 1:1 mixing ratio, these conditions resulted in the maximum volatile solids consumption of 26.26% in 5 days. The volatile solids consumption and 34.47% water removal rate of the trial had contributed to a total of 64.13% weight loss. The weight loss was even higher than that of a conventional biodrying system which was conducted for more than 14 days.

Addressing supply uncertainties using multi-period stochastic economic evaluation: A graph-theoretic aided element targeting approach

The challenges to commercialize biomass industry includes biomass supply shortage which is dependent on geographical location and seasonality. Most of the present biomass supply chain studies had not considered incorporation of supply chain uncertainties that may lead to overestimation of financial performance. Therefore, a hybrid framework was proposed via integration of stochastic Monte Carlo Simulation model with element targeting approach (Biomass Element Life Cycle Analysis, BELCA-P-graph model) to perform scheduling and economic analysis for the biomass supply chain. The BELCA-P-graph model aimed to generate a baseline for the feedstock ratio of each input biomass. This was then input into the stochastic model, capable of estimating the financial probability of the supply chain while incorporating supply chain uncertainties (i.e., biomass element characteristics, transportation-related parameters, raw material pricing, biomass availability, market demand, and selling price of final product). Results showed that biomass shortage had decreased the mean Net Present Value (NPV) of the base case scenario (without consideration biomass supply shortage) by 1.39%–12.21%. Storage capacity consideration had decreased the mean NPV by 11.59%–12.21%. The sensitivity analysis found that syngas demand and syngas selling price uncertainty offered significant impact on the mean NPV outcome. • Integrated Monte Carlo model with BELCA-P-graph model was presented. • Six supply chain uncertainties are modelled using Monte Carlo simulation. • Biomass shortage reduced mean NPV of base case up to 12.21%. • Implementation of storage resulted in a further reduction in mean NPV.

Thermodynamic Study of One-step Production from Isobutene to Methyl Methacrylate

Methyl methacrylate (MMA) has emerged as an essential industrial monomer. However, the toxic by-production and shortage supply of MMA in the global market has gained great attention. Herein, a one-step synthesis to produce MMA from isobutene via a direct oxidative esterification process has been demonstrated to curb the aforementioned downsides. Thermodynamic analysis via Gibbs free energy minimization method proved the feasibility of this route via the equilibrium constant. Despite tert-butanol and isobutane showed higher equilibrium constant than isobutene, they should be avoided. Isobutane is highly flammable while the precursor of tert-butanol is exorbitant. Thus, isobutene was selected for the equilibrium compositions screening. Isobutene conversion was 90% and 15% MMA yield at 700 °C and IBN: O2: MeOH ratio with 1:7:1. This route is mainly limited by the generation of side reactions from the reaction of CH3OH and O2. By varying the feedstock ratio at 1:2:1, the MMA yield increased to ~25%. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Performance assessment of the co-gasification for sustainable management of municipal solid waste: Moroccan Case

In the quest of virtuous energy system, clean energy production poses important environmental, social, and financial challenges. Among the potentially useful energy carriers, hydrogen emerges as a serious alternative to fossil fuels. Hydrogen is a clean energy vector whose use is likely to undergo significant development in the medium and long term. This article describes the current situation of municipal solid waste generation and management in Morocco. Additionally, a co-gasification plant model for hydrogen production from municipal solid waste and biomass blends was developed in Aspen Plus. A parametric analysis was carried out to study the effect of various parameters such as the temperature of gasification and the steam to feedstock ratio on syngas composition. The main findings show an increase in hydrogen molar fractions for higher temperatures (optimal values being achieved for ∼750 °C) and steam to feedstock ratios ≥1.2. The present model of the co-gasification plant could be further improved by adding a water–gas-shift reactor. This process intensification technique can contribute to the production of sustainable alternatives to the actual predominant fossil-based fuels.

Parametric studies over a plasma co-gasification process of biomass and coal through a restricted model in Aspen plus

Plasma gasification is considered an emerging technology within the so-called waste-to-energy technologies. The pure equilibrium models have been failing to estimate the amounts of the syngas components, especially the methane quantity. In this investigation, a restricted or quasi-equilibrium model was developed in Aspen Plus® to evaluate the performance of the plasma co-gasification process of biomass and coal. The developed model was validated against literature data. A comprehensive parametric study was performed considering the variation of the equivalence ratio, biomass ratio, temperature, and steam to feedstock ratio on the quality of syngas and hydrogen production. Three gasifying agents (air, steam, and oxygen) were used. The syngas lower heating value and the cold gas efficiency are taken as a measure of the syngas quality and process efficiency. The developed restricted model shows to estimate the amount of methane much closer to the experimental data than pure equilibrium models. The highest amount of hydrogen was obtained for steam followed by pure oxygen and lastly for the air as gasifying agents. The use of coal in the feedstock mixture allows obtaining higher LHV of the syngas and CGE of the process. The results of this parametric study represent a humble contribution to the increase of plasma gasification technology market penetration.

Catalytic co-pyrolysis of solid wastes (low-density polyethylene and lignocellulosic biomass) over microwave assisted biochar for bio-oil upgrading and hydrogen production

Metal catalysts are unavoidable within the process of catalytic pyrolysis, a part of hydrogen production; as a result, the reuse and disposal of these materials are problems that need to be solved. Biochar, with its extensive sources, large specific area, and developed pores, has the potential to be developed in this catalytic area. In this study, we used microwave-assisted corn stover biochar as a catalyst in the co-pyrolysis of Douglas Fir (DF) and low-density polyethylene (LDPE) in order to investigate its catalytic effects. The results showed that the biochar significantly increased the selectivity of hydrogen (H2) in the syngas, and the highest selectivity that could be achieved was 72 vol% at 650 °C, with a biochar (BC)/feedstock ratio of 4. Furthermore, the application of biochar decreased the wax yield and contributed to the good selectivity of aromatics. The biochar developed in this study was also proven to show good reusability, as even after 10 times of reuses, the biochar still achieved a yield of H2 over 50 vol%.

A techno-economic study to evaluate the impacts of feedstock ratio on commercial scale co-pyrolysis plants of biomass and waste tire

Six types of commercial-scale pyrolysis and co-pyrolysis plants for rice straw (RS) and waste tire (WT), with a capacity of 20 tons/hour, have been modeled based on experimental data. The impact of a range of feedstock ratios on the techno-economic performance of the plants is comprehensively studied. The capital investment of plants ranged between $17.0 and $19.9 million with Plant A (RS only) having the lowest and Plant E (20 % RS and 80 % WT) having the highest value. The operating cost was found to be lowest for Plant A and highest for Plant F (100 % WT) due to the procurement cost of WT. Pyrolytic-oil and char are the main revenue streams while gases are combusted to generate the energy required for the pyrolysis reactor and preheating of feedstock. Plant E is the most economical alternative with the highest gross margin, highest net present value and lowest payback time of 7.06%, $ 5.63 million and 6.23 years respectively. Sensitivity analysis indicates that oil selling price and WT procurement cost are the most influential factors affecting economic returns.

Catalytic co‐pyrolysis of low‐density polyethylene (LDPE) and lignin for jet fuel range hydrocarbons over activated carbon catalyst

The catalytic conversion of low-density polyethylene (LDPE) and lignin over activated carbon into jet fuel range hydrocarbons was studied. A fixed bed furnace was used to investigate the impacts of temperature, LDPE to lignin ratio, and catalyst to feedstock ratio on the composition of bio-oils, and up to 100 area% jet fuel range hydrocarbons can be acquired from the catalytic co-pyrolysis of LDPE and lignin. The results showed that the activated carbon has an excellent catalytic performance to convert LDPE and lignin into jet fuel range hydrocarbons. The properties of activated carbon catalyst were characterized by nitrogen gas adsorption, Fourier transform infrared spectrometer, and scanning electron microscope. There is a synergistic effect between the higher pyrolysis temperature and the acid sites of activated carbon on the dissociation and conversion of alkanes to form the aromatics. In addition, the yield of jet fuel range hydrocarbons could be enhanced by the synergistic effect of LDPE on the catalytic conversion of lignin. This work provided an environment friendly, economical, convenient, simple, and effective route to acquire jet fuel range hydrocarbons from daily waste plastics and biomass.