Biomass-derived Synthesis Gas Research Articles

Techno-economic analysis of hydrogen enhanced methanol to gasoline process from biomass-derived synthesis gas

In this paper, the implications of the use of hydrogen on product yield and conversion efficiency as well as on economic performance of a hydrogen enhanced Biomass-to-Liquid (BtL) process are analyzed. A process concept for the synthesis of fuel (gasoline and LPG) from biomass-derived synthesis gas via Methanol-to-Gasoline (MtG) route with utilization of carbon dioxide from gasification by feeding additional hydrogen is developed and modeled in Aspen Plus. The modeled process produces 0.36 kg fuel per kg dry straw. Additionally, 99 MW electrical power are recovered from purge and off gases from fuel synthesis in CCGT process, covering the electricity consumption of fuel synthesis and synthesis gas generation. The hydrogen enhanced BtL procces reaches a combined chemical and electrical efficiency of 48.2% and overall carbon efficiency of 69.5%. The total product costs (TPC) sum up to 3.24 €/kg fuel. Raw materials (hydrogen and straw) make up the largest fraction of TPC with a total share of 75%. The hydrogen enhanced BtL process shows increased chemical, energy and carbon efficiencies and thus higher product yields. However, economic analysis shows that the process is unprofitable under current conditions due to high costs for hydrogen provision.

Upgrading of Bio-Syngas via Steam-CO2 Reforming Using Rh/Alumina Monolith Catalysts

Steam-CO2 reforming of biomass derived synthesis gas (bio-syngas) was investigated with regard to the steam concentration in the feed using Rh-loaded alumina foam monolith catalysts, which was also accompanied by thermodynamic equilibrium calculation. With 40 vol % steam addition, steam methane reforming and water gas shift reaction were prevailed at the temperature below 640 °C, above which methane dry reforming and reverse-water gas shift reaction were intensified. Substantial change of activation energy based on the methane conversion was observed at 640 °C, where the reaction seemed to be shifted from the kinetic controlled region to the mass transfer controlled region. At the reduced steam of 20 vol %, the increase in the gas velocity led to the increase in the contribution of steam reforming. Comparing to the absence of steam, the addition of steam (40 vol %) resulted in the increase in the production of H2 and CO2, which in turn increased the H2/CO ratio by 95% and decreased the CO/CO2 ratio by 60%. Rh-loaded alumina monolith was revealed to have a good stability in upgrading of the raw bio-syngas.

Thermal Effects of Natural Gas and Syngas Co-Firing System on Heat Treatment Process in the Preheating Furnace

Preheating furnaces, which are commonly used in many production sectors (e.g., iron and steel), are simultaneously one of the most energy-intensive devices used in the industry. Partial replacement of natural gas with biomass-derived synthesis gas as a fuel used for heating would be an important step towards limiting industrial CO2 emissions. The time dependent computational fluid dynamics (CFD) model of an exemplary furnace was created to evaluate whether it is possible to obtain 40% of energy from syngas combustion without deterioration of thermal parameters of the treated load. As an outcome, a promising method to organize co-firing in the furnace was indicated. The obtained results show that the co-firing method (up to 40% thermal natural gas replacement with syngas), assuming low air-to-fuel equivalence ratio (λNG = 2.0) and even distribution of power among the furnace corners, lead to satisfactory efficiency of the heat treatment process—the heat transferred to the load exceeds 95% of the heat delivered to the load in the reference case), while carbon dioxide emission is reduced from 285.5 to 171.3 kg CO2/h. This study showed that it is feasible (from the heat transfer point of view) to decrease the environmental impact of the process industries by the use of renewable fuels.

Biyokütle Kaynaklı Sentez Gazından Hidrojen Üretimine Entegre Bir Güç Sisteminin Modellenmesi

Ülkemizde bazı bölgelerde bulunan zengin jeotermal enerji kaynaklarının değerlendirilmesi, yerli ve yenilenebilir enerji üretimine imkân vermektedir. Aynı zamanda, bu bölgelerde önemli miktarlarda biyokütle atık potansiyellerinin bulunması, bir enerji taşıyıcısı olan hidrojen gazı üretimi için de kaynak oluşturmaktadır. Biyokütlenin gazlaştırılması sonucunda elde edilen sentez gazı kullanılarak yüksek saflıkta hidrojen üretimi yapılabilmektedir. Bu çalışma kapsamında, jeotermal ve biyokütle enerji kaynaklarının birlikte değerlendirilmesi hedeflenmiştir. Jeotermal kaynaklara sahip olan Manisa Alaşehir bölgesinde kurulabilecek biyokütle kaynaklı sentez gazından hidrojen üretimine entegre bir güç üretim sistemi modellenmiştir. Bunun için, sentez gazı debisi 3 kg/s olarak belirlenmiştir. Bu temelde, önerilen sistemin, Aspen HYSYS simülasyon programı kullanılarak benzetimi yapılmış ve sistemin yapılabilirliği araştırılmıştır. Benzetim ve analiz çalışmaları sonucunda, belirlenen kapasite için, hidrojen üretim sistemi ile birleşik tasarlanan bir organik Rankine çevrimi kullanılarak 729 kWe elektrik enerjisi üretilebilmektedir. Bu sayede, hidrojen üretim prosesinin tükettiği enerjinin bir kısmı karşılanabilmektedir. Bununla birlikte, ilave edilen jeotermal kaynaklı bir güç santrali ile de geri kalan enerji ihtiyacı sağlanabilmektedir. Önerilen sistemin kendi iç tüketimi toplamda 14.886 kWe’dir. Organik Rankine ve jeotermal kaynaklı güç çevrimlerinin toplam gücü ise 47.649 kWe olarak bulunmuştur. Bu çalışmanın, biyokütle ve diğer yenilenebilir kaynakları içeren benzer hibrit sistemlerin ön tasarım çalışmalarına katkı sağlayabileceği değerlendirilmektedir.

Bifunctional catalysts based on colloidal Cu/Zn nanoparticles for the direct conversion of synthesis gas to dimethyl ether and hydrocarbons

Hybrid catalysts were prepared using well-defined, colloidal Cu/Zn-based nanoparticles as building units. The nanoparticles were immobilized on acidic supports (i.e., γ-Al2O3, HZSM-5, and HY) to yield a series of bifunctional catalysts with a close proximity of active sites for both methanol synthesis and its further conversion to dimethyl ether (DME) or hydrocarbons (HCs). By this model kit principle, a high comparability of the bifunctional catalysts was ensured. The catalysts were characterized in depth regarding their structure and catalytic performance in the conversion of CO-rich synthesis gas. In situ XAS studies demonstrated the formation of the active phase under reducing conditions. The present study revealed important material parameters to control activity and selectivity of the bifunctional catalysts either towards DME or liquefied petroleum gas (LPG) products in the direct conversion of simulated biomass-derived synthesis gas. In particular, Cu loading, pore structure and Si:Al ratio were investigated.

Syngas feed of micro gas turbines with steam injection: Effects on performance, combustion and pollutants formation

In this work, the performance of a 100kW Micro Gas Turbine (MGT) fed by biomass-derived Synthesis gas (S) have been assessed using a simulation algorithm, consisting of a set of equations describing the behavior of the turbomachines, the pressure losses in each component, as well as the consumption of the other auxiliary devices. An additional algorithm using Cantera’s library has been developed in order to study the combustion kinetics and to assess the MGT emissions with S and with natural gas (NG) feed.The electric power output, achieved using S with a Lower Heating Value (LHV) of about 9MJ/kg, turns out to be similar to that achieved with NG, if a proper fuel injection strategy is adopted; efficiency is slightly lower, mainly because of the variation of the working fluid composition which involves an increase of the heat required to run the machine. In this work, the effect of the steam injection on the MGT performance characteristics has been also investigated with both NG and S. Steam injection allows to obtain higher power and efficiencies at the rated rotational speed. Attention must be paid to the risk of the compressor stall, especially when using S, as the mass flow rate processed by the compressor decreases significantly. As regards the pollutants’ emission, S combustion involves a reduction of NOX emissions of about 75%, while CO emissions slightly increase with respect to natural gas combustion. However, it was found that, with a proper fuel and steam injection strategy, the concentration of the polluting compounds can be further reduced.Moreover, another advantage of adopting the steam injection technique lies in the increased flexibility of the system: according to the users’ needs, the discharged heat can be exploited to generate steam, thus to enhance the electric performance, or to supply thermal power.

Influence of the Syngas Feed on the Combustion Process and Performance of a Micro Gas Turbine with Steam Injection

Abstract Micro gas turbines (MGT) are promising devices for distributed cogeneration, offering a great opportunity for primary energy savings and reduction of pollutants and greenhouse gas emissions. The possible use of low-carbon fuels like syngas from biomass gasification, allows to further reduce the carbon footprint of distributed generation and to reduce the energy supply chain. In this work, the performance of a 100 kW MGT fed by natural gas and a biomass-derived synthesis gas have been assessed through a Matlab simulation algorithm, both in standard and steam injection configuration (STIG). An additional Matlab algorithm using Cantera's library has been created in order to study the combustion kinetics of the two fuels and to assess the turbine's emissions. Results show that for equal thermal power fed in the combustor, syngas combustion involves a reduction of NOx emissions of about by 75%, while CO emissions slightly increase with respect to natural gas combustion; in terms of performance, the use of syngas slightly reduces the power output and the efficiency of the machine. It was also found that the STIG configuration with the recovery of the heat content of the exhaust allows to inject up to 56 g/s of steam. A proper injection strategy is proposed and the electric power enhancement is evaluated in as much as 24%; also electric efficiency is slightly increased up to 29%. Moreover, steam injection in the combustion chamber, allows to dramatically reduced CO and NOx emissions.

Passivation and reactivation of catalyst systems for the single step synthesis of dimethyl ether from CO-rich synthesis gas

A methanol catalyst based on Cu/ZnO/Al2O3 (CZA) was prepared and mixed with four different solid acids, a pure γ-Al2O3, a SiO2-doped γ-Al2O3, an AlPO4-doped γ-Al2O3 and the zeolite H-MFI 400, respectively. These admixed catalyst systems were tested in the direct synthesis of dimethyl ether from CO-rich synthesis gas (CO:H2=1), which is typical for biomass-derived synthesis gas. Reactions were carried out in a laboratory plant at 250°C and 51bar for 120h time-on-stream followed by catalyst passivation with O2 and regeneration by hydrogenation. After catalyst regeneration, the reaction was run again for another 72h. The catalyst system containing the zeolite exhibited highest CO-conversion. However, all catalysts showed a drop of activity after the passivation- and regeneration-process and the system with the SiO2-doped γ-Al2O3 showed the lowest loss of activity. Investigation of the catalysts after reaction by N2O-pulse chemisorption and XRD revealed that agglomeration of catalyst species took place leading to an increased Cu0-particle size for all systems. This phenomenon was less pronounced in the case of the system containing the SiO2-doped γ-Al2O3. Thus, the main cause of catalyst deactivation was found to be sintering of the catalytically active components.

Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro

The production of higher alcohols over a sulfidized molybdenum catalyst (MoS2) using a biomass-derived synthesis gas has been studied at Güssing for several years. The mixed alcohol (MA) pilot plant uses synthesis gas provided by the biomass-based combined heat and power plant (CHP) Güssing. Parameter variations were carried out wherein temperature, space velocity and gas composition were varied to evaluate the impact on CO conversion, product distribution and yield. The influence of side reactions to hydrocarbons was also a research objective. A sufficient amount of experimental data was obtained during these experiments. Evidence for the influence of various reaction parameters was found, but the mass balance could not be closed. A mathematical model of the MA synthesis reactor was developed using the stationary equation-orientated flow sheet simulation software IPSEpro. This publication gives an overview of modeling the MA reactor and condenser unit and testing the model with example calculations. Validated experimental results from 2012 parameter variation are shown and a comparison between experimental and validated quantities is carried out. A comparison with literature data shows that the observed tendencies are in good correlation to literature. The developed reactor model was enabling the possibility for carrying out a validation of the experimental data. IPSEpro uses the method of least-squares to obtain the approximate solution of the overall determined system. The established model was very close to the actual MA pilot plant. The model is very accurate about MA liquid product compositions and all measured flows.

Influence of ethylene on the formation of mixed alcohols over a MoS2 catalyst using biomass-derived synthesis gas

Since 2011, a pilot plant for the production of mixed alcohols (MAs) from biomass-derived synthesis gas has been in operation. The pilot plant uses synthesis gas provided by a biomass-based combined heat and power plant (CHP) in Gussing, in which the fixed bed reactor is filled with a sulfidized molybdenum catalyst (MoS2). The advantage of a sulfidized catalyst is resistance to sulfur components. Sulfur resistance significantly lowers the operating costs of such a plant. The main parts of the mixed alcohol synthesis plant in Gussing are a steam reforming unit, a glycol scrubber, a compression step, a fixed bed reactor for the synthesis itself, a condensation vessel for the separation of alcohols from the gas stream, and an expansion valve. The main aim of this project in the last year was to perform parameter variation to investigate the optimal operation point of the plant and to use these parameters to conduct long-time trials over several days. Parameter variation showed the impact of reaction temperature, pressure, and space velocity on product yield and distribution. The influence of the gas composition on the product distribution and side products was also investigated. This study was dedicated to investigating the influence of the ethylene content in the synthesis gas on the formation of propanol and ethyl mercaptan (C2H6S). During the experiments, several liters of MAs were produced. The alcohols consisted mainly of alcohols from carbon numbers between one and three. One of the main results of the first experiments was that the ethylene content in the synthesis gas has a high impact on the product distribution and is also responsible for side reactions to sulfur components.

Evaluation of Sorbents for High Temperature In Situ Desulfurization of Biomass-Derived Syngas

In a preparative study, the use of different sorbent materials for in situ desulfurization of biomass derived synthesis gas is evaluated. Results of phase equilibrium calculations using FactSage version 6.4 for the H2S equilibrium concentration with a variation of different parameters are compared to values for the residual H2S content found in literature. The focus is strictly set on a high temperature, high steam application for biomass-derived syngas conditions. Possible synergistic effects between different sorbent components and deviations from simulated results are discussed subsequently. The use of copper-based sorbent material turns out to be promising due to a predicted positive impact of high steam conditions for sorption equilibria. Results for the implementation of a CaO–BaO mixed phase sorbent are confirmed, qualifying this material combination as a promising candidate for in situ application. Equilibrium calculations predict a desulfurization of syngas to a sulfur level of 2.1 ppmv H2S at a steam content of about 40 vol % and 820 °C which is sufficient for further catalytic gas processing applications.

High-Temperature Sulfur Removal from Biomass-Derived Synthesis Gas over Bifunctional Molybdenum Catalysts

Removal protocol: Molybdenum-based catalysts are efficient for the removal of H2S and organic sulfur species from gasified biomass at high temperatures. Water, which is ubiquitous in biomass, impedes desulfurization. In situ X-ray absorption spectroscopy analysis shows that H2S is removed from the biomass-derived producer gas through the sulfidation of MoO3 to MoS2, whereas MoO2 is the active phase for the removal of thiophene.

Effect of Molybdenum on the Sulfur-Tolerance of Cerium–Cobalt Mixed Oxide Water–Gas Shift Catalysts

As traditional sources of energy become depleted, significant research interest has gone into conversion of biomass into renewable fuels. Biomass-derived synthesis gas typically contains concentrations ranging from ~30 to 600 ppm H2S. H2S is a catalyst poison which adversely impacts downstream processing of hydrogen for gas-to-liquid plants and the deactivation of water–gas shift catalysts by sulfur is typical. Novel catalysts are needed to remain active in the presence of sulfur in order to boost efficiency and mitigate costs. Previous studies have shown molybdenum to be active in concentrations of sulfur >300 ppm. Cobalt has been shown to be active as a spinel in concentrations of sulfur <240 ppm. Ceria has received attention as a catalyst due to its oxygen donating properties. In this study, mixed oxide catalysts were synthesized via Pechini’s method into various blends of metal oxide solutions. Activity testing at low steam-to-carbon ratios (1:1) produced near equilibrium conversions at a GHSV of 6,300 h−1 and over a temperature range of 350–400 °C for a Ce–Co mixed oxide even after an 800 ppm sulfur treatment. The addition of molybdenum to the Ce–Co base had little effect on sulfur tolerance, but it did lead to a reduction in selectivity for methanation. Specific surface areas generally increased following the sulfur treatments and X-ray diffraction patterns confirmed that bulk sulfiding did not occur.

Effects of sodium and sulfur on catalytic performance of supported iron catalysts for the Fischer–Tropsch synthesis of lower olefins

The Fischer–Tropsch synthesis of lower olefins (FTO) is an alternative process for the production of major chemical building blocks from natural gas, coal, or biomass-derived synthesis gas. The addition of low concentrations of sulfur plus sodium to Fe/α-Al2O3 resulted in catalysts with high C2–C4 olefins selectivity (∼50%C), enhanced catalytic activity, and decreased methane production (<20%C) when the reaction was carried out at 340°C, 20bar and H2/CO=1. Sodium reduced methane selectivity by increasing the chain growth probability while sulfur probably reduced the hydrogen coverage of the catalyst resulting in even lower methane selectivities and higher olefin content of the products. The addition of extra sodium resulted in a detrimental effect on catalytic activity while favoring the formation of carbon deposits. Our results show that the nature and concentration of the promoters play a key role in the design of FTO catalysts with optimum catalytic performance.

Iron nanoparticles in situ encapsulated in biochar-based carbon as an effective catalyst for the conversion of biomass-derived syngas to liquid hydrocarbons

Biochar, a by-product from the fast pyrolysis of pine wood, was used as the support material for the synthesis of carbon-encapsulated iron nanoparticles. The nanoparticles were characterized for physicochemical properties by multiple morphological and structural methods (e.g., SEM, TEM, XRD, FTIR, and TPD). The Fischer–Tropsch synthesis (FTS) process was carried out to evaluate the catalytic activity of the nanoparticles on conversion of biomass-derived synthesis gas (bio-syngas) to liquid hydrocarbons. Characterization results revealed that the nanoparticles had core–shell structures with iron in situ encapsulated within a graphitic shell. Moreover, significant amounts of iron carbide (mainly Fe3C) were formed as an interface between the carbonaceous shell and the iron core. FTS tests indicated that such carbon-encapsulated iron nanoparticles possessed a high activity on conversion of bio-syngas and good selectivity towards liquid hydrocarbons (of which olefins were the dominant product). Over a 1500 h testing period, the nanoparticles showed striking stability against deactivation, with CO conversion maintained at about 95% and liquid hydrocarbon selectivity at about 68%.

Thermodynamics Simulation of Ethanol Synthesis via Biomass Gasification

Based on Aspen Plus software platform, a simulation of ethanol synthesis from biomass-derived synthesis gas processed on the assumption of both physical and thermodynamic equilibrium. The influences of these conditions such as temperature, reactor pressure and the H2 to (CO+CO2) mole ratio in the feed gas on CO and CO2 conversion and ethanol yield were investigated. The results showed that reaction temperature, pressure and synthesis gas composition have the most important effect on ethanol synthesis behavior. In this process, low temperature and high pressure would be advantageous for ethanol production.

Influence of Temperature and Pressure Change on Adiabatic and Isothermal Methanation Processes

Abstract Energy plans of many countries anticipate an increased use of biomethane for energy supply, i.e., in power and heat production as well as in the transport sector. Existing infrastructure of natural gas storage, supply and application provides a good platform to facilitate transfer to biomethane utilization on a larger scale. One key element of the biomethane system is the upgrade of the biomass-derived synthesis gas originating from different sources, to a quality of natural gas (SNG - Synthesis Natural Gas) via the methanation process for further injection into the natural gas grid.. The maximisation of efficiency of the methanation process is of critical importance in order to make biomethane technology viable for wider application. The aim of the study was to improve efficiency of the methanation process by finding the optimum temperatures and pressure. Theoretical modelling of adiabatic and isothermal methanation processes by using thermodynamic equilibrium calculations was introduced as a method for the study. The results show the impact of temperature and pressure changes on the overall efficiency of methane production. It can be concluded from the study that knowledge about the relation between temperature, pressure and the efficiency of the methanation process makes it possible to optimize the process under various biomass synthesized gas input conditions.

Recent Patents on the Conversion of Biomass to Fuels via Synthesis Gas

Synthesis gas serves as a raw material for a variety of processes such as methanol production, Fischer-Tropsch synthesis of hydrocarbons or hydroformylation reactions. It can be obtained by reforming hydrocarbons, in particular methane, by gasification of coal or by conversion of biomass. Biomass can be gasified either directly or after pretreatment, e.g. by pyrolysis. The use of biomass as feedstock, especially waste biomass, is favorable since its availability is, in contrast to fossil resources, not exhaustible, and it can contribute to a decrease of CO2 emissions. A prominent strategy is the production of methanol, ethanol or dimethyl ether (DME) from biomass-derived, i.e. carbon monoxide-rich, synthesis gas. These are valuable fuels and chemicals, which can be converted to a series of other products. Within this article recent developments in the synthesis of ethanol and higher alcohols as well as DME from biomass-derived synthesis gas are surveyed with a strong focus on the patent literature from the year 2000 onwards. Furthermore, processes employing methanol as feedstock, e.g. synthesis of olefins and gasoline, are also evaluated. Keywords: Alcohols, biomass, diesel, DME, ethanol, ethylene, fuels, gasoline, hydrocarbons, methanol, MTG, MTO, olefins, propylene, synthesis gas

Analysis of a Micro Gas Turbine Fed by Natural Gas and Synthesis Gas: MGT Test Bench and Combustor CFD Analysis

In recent years, the interest in the research on energy production systems fed by biofuels has increased. Gaseous fuels obtained through biomass conversion processes such as gasification, pyrolysis and pyrogasification are generally defined as synthesis gas (syngas). The use of synthesis gas in small-size energy systems, such as those used for distributed micro-cogeneration, has not yet reached a level of technological maturity that could allow a large market diffusion. For this reason, further analyses (both experimental and numerical) have to be carried out to allow these technologies to achieve performance and reliability typical of established technologies based on traditional fuels. In this paper, a numerical analysis of a combustor of a 100-kW micro gas turbine fed by natural gas and biomass-derived synthesis gas is presented. The work has been developed in the framework of a collaboration between the Engineering Department of the University of Ferrara, the Istituto Motori - CNR (Napoli), and Turbec S.p A. of Corporeno di Cento (FE). The main features of the micro gas turbine Turbec T100, located at the Istituto Motori - CNR, are firstly described. A decompression and distribution system allows the feeding of the micro gas turbine with gaseous fuels characterized by different compositions. Moreover, a system of remote monitoring and control together with a data transfer system has been developed in order to set the operative parameters of the machine. The results of the tests performed under different operating conditions are then presented. Subsequently, the paper presents the numerical analysis of a model of the micro gas turbine combustor. The combustor model is validated against manufacturer performance data and experimental data with respect to steady state performance, i.e., average outlet temperature and emission levels. A sensitivity analysis on the model capability to simulate different operating conditions is then performed. The combustor model is used to simulate the combustion of a syngas, composed of different ratios of hydrogen, carbon monoxide, methane, carbon dioxide and water. The results in terms of flame displacement, temperature and emission distribution and values are analyzed and compared to the natural gas simulations. Finally, some simple modifications to the combustion chamber are proposed and simulated both with natural gas and syngas feeding.

Gasoline-range hydrocarbon production using biomass derived synthesis gas over Mo/H+ZSM-5

Biomass-derived hydrocarbons that include gasoline, diesel, and jet fuel can help replace finite fossil fuel hydrocarbons of the same range. The objective of this study was to prove that gasoline-range hydrocarbons could be created from gasified woody biomass (producer gas) using thermochemical conversion with a Mo/H+ZSM-5 catalyst and compare these results to gasoline-range hydrocarbons created from contaminate-free synthesis gas (syngas). This study was also performed to help understand obstacles related to a scaled-up reactor system using a Mo/H+ZSM-5 catalyst with producer gas. The CO conversion, C selectivity and amount of product created from each type of gas were examined. Contaminate-free syngas composed of 40% H2, 20% CO, 12% CO2, 2% CH4, and 26% N2 (2:1 H2–CO) was used to test near ideal stoichiometric molar values comparable to producer gas for gas to liquid creation. Contaminate-free syngas composed of 19% H2, 20% CO, 12% CO2, 2% CH4, 47% N2 and producer gas composed of 19% H2, 20% CO, 12% CO2, 2% CH4, and 46% N2 was also used in this study to determine the feasibility of using gasified biomass syngas to produce gasoline-range hydrocarbons. The liquid hydrocarbon (organic phase) yield for the 2:1 syngas, 1:1 syngas and producer gas was 0.00844±0.00315, 0.00327±0.00101, and 0.00040±0.00058%, respectively.