Biomass Gasification Plant Research Articles

MODELLING AND EXERGETIC TECHNO-ECONOMIC ANALYSIS OF A SYSTEM FOR HYDROGEN PRODUCTION FROM EMPTY BANANA FRUIT BUNCH

One of the most effective and reliable methods for generating hydrogen fuel using biomass is the gasification method. However, utilization of different biomass feedstock has the ability to withstand production of syngas which can be utilized for several applications. The study investigated the feasibility of hydrogen from Empty Banana Fruit Bunch (EBFB) biomass and the energetic techno-economic analyses of biomass gasification plant with a developed system simulation model aspen plus simulator V11. Five chemical reactions were used in production process and were simulated in ASPEN Plus simulator through biomass gasification method which aimed in removing C, CO, CO2, CH4, and H2O to convert them into hydrogen gas. However, the total exergy out divided by the total exergy in gives exergy efficiency. Hence, total exergy out subtracted from total exergy in depicts exergy destruction. The exego-economic method utilized in the exergo-economic analyses is the Specific Cost method (SPECO). The results affirmed that 80.465 kg/hr of H2 can be produced from 2000 kg/hr of empty banana fruit bunch at every 39.92 k.mol/hr mole flow of EBFB. However, at a temperature below 900 0C CO decreases, CO2 increases. Above 1000 0C, CO increases hence decreases CO2 emission. The system total exergy in, total exergy out, percentage exergy efficiency, and exergy destruction are 4534.77 kJ/kg, 3857.295 kJ/kg, 0.8506 %, and 677.475 kJ/kg. Hence, system exergy stream cost rate, component-related cost rate, component-related cost difference, and component exergoeconomic factor are 407527.644$/h 1555.57$/h, 0.5679%, and 0.9089% respectively. Further studies may concentrate on how to reduce CO through regulated temperature and pressure differences so as to increase the quantity of hydrogen production.

Hot syngas cleanup for pilot two-stage fluidized bed steam-oxygen biomass gasification plant

Biomass gasification as a renewable energy technology has been a widely explored research and development area. The efficient and economic removal of harmful components, particularly tars, in raw syngas from the biomass gasifier is still a major challenge. In this study, a novel two-stage fluidized bed pilot-scale gasifier has been developed to enhance the steam-oxygen biomass gasification to generate low-tar syngas; while, a prototype hot syngas cleanup system has been designed, built and tested to further reduce the tar content and purify the syngas from the biomass gasifier for downstream applications. The results showed that the tar removal efficiency by a catalytic tar cracker using an iron-based bauxite residue derived catalyst prepared in-house can reach 82.8–98.0% at reaction temperatures of 678–801°C, and 90.6–98.0% at 784–801°C, respectively. Furthermore, the tar content of the cleaned syngas can be as low as 0.10–0.65 g/Nm3 when the raw syngas tar content is 2.59–27.71 g/Nm3. In the case of syngas composition, H2 content ranged from 32.7% to 48.0%, CH4 from 2.8% to 4.8%, CO from 26.3% to 35.7%, and CO2 from 18.4% to 33.9%. The H2/CO molar ratio varies from 1.0 to 1.8, requiring the application of the water–gas shift reaction to increase the H2/CO ratio to 3 for downstream methanation to produce renewable natural gas.

Cogeneration processes based on giant reed gasification combined with ORC and district heating for heat recovery: Comparative energy and exergy analysis

This research work develops a comprehensive exergy and energy assessment of a cogeneration process using Giant Reed as feedstock, which consists of a biomass dryer, a fluidized bed gasifier, an internal combustion engine operating in a cogeneration mode (CHP), and two different users for the cogenerated heat. One process layout uses cogenerated heat in a district heating network (CHP + DH layout). In the second process layout, the cogenerated heat produces additional electricity through an Organic Rankine Cycle (CHP + ORC layout). In addition to the performance of reed gasification (cold gas efficiency about 0.6), the results showed that the highest rational efficiency was reached in the cogeneration unit, while the highest relative irreversibilities were found in the gasifier and the dryer. The overall energy efficiencies are 0.46 and 0.22 for the CHP + DH and CHP + ORC layouts, respectively, while the overall exergy efficiencies are 0.21 and 0.20. The difference in the sustainability index is just 2 %. The results and methods of this research work can be used to properly design Giant Reed (or similar biomass) gasification plants and bioenergy systems for combined heat and power production, and developing case-studies considering the sustainable use of this feedstock according to a thermodynamic approach based on the second principle.

Life Cycle Assessment of a Wood Biomass Gasification Plant and Implications for Syngas and Biochar Utilization

The growing attention regarding the environmental challenges in the energy sectors pushes the industrial system toward the investigation of more sustainable and renewable energy sources to replace fossil ones. Among the promising alternatives, biomass is considered a valid source to convert the system and to reduce the fossil fraction of the national energy mixes, but its multiple potential uses need an environmental evaluation to understand the actual benefit when it is used as an energy resource. For this purpose, life cycle assessment (LCA) is applied to a wood biomass gasification system aimed to produce electricity and heat generated after the combustion of the produced syngas and the management of the biochar. The aim is to provide a quantitative comparison of (i) a baseline scenario where wood biomass is sourced from waste and (ii) a second scenario where wood biomass is drawn from dedicated cultivation. A further evaluation was finally applied to investigate the environmental implications associated with the biochar composition, assuming it was used on land. The proposed strategies resulted in an environmental credit for both the examined scenarios, but the outcomes showed a net preference for the baseline scenario, resulting in better environmental performances for all the examined categories with respect to the second one. It underlines the potentialities of using waste-sourced biomass. However, according to the Climate Change category, if on-site dedicated biomass cultivation is assumed for the second scenario, the baseline is considered preferable only if the biomass transportation distance is <600 km, which is estimated as a theoretical distance for scenarios to break even. Finally, biochar composition proved a particular concern for toxicity-related categories. This study highlights the importance of applying objective and standardized methodologies such as LCA to evaluate energy production systems based on alternative sources and to support decision-making toward achieving sustainability goals.

Optimal sizing of hybrid PV–diesel–biomass gasification plants for electrification of off-grid communities: An efficient approach based on Benders’ decomposition

Nowadays, millions of people in remote areas do not enjoy an uninterrupted power supply due to the lack of connectivity to the main power grid. Under such circumstances, the only feasible way to access electricity is typically local power generation, often relying on diesel engine–generator sets or photovoltaic arrays. However, on many occasions, this configuration does not fully exploit all available local resources, including biomass. Indeed, most isolated areas have access to local biomass production from agricultural activities, which can be used for local electricity generation through gasification. This paper addresses this challenge by developing an innovative optimal sizing tool for hybrid power plants integrating biomass gasifiers, specifically designed for isolated areas with access to local biomass production. The novel approach models the particular features of biomass gasification technologies, including long on/off times or restrictive ramping limits. To this end, an efficient methodology based on representative weeks is proposed, which is combined with a solution strategy based on the multi-cut Benders’ decomposition, thus resulting in a tractable framework that can deal with a huge amount of data efficiently. One of the most salient features of the new proposal is the consideration of local biomass production, which is included in the methodology through an original algorithm. Accordingly, a certain amount of biomass is sourced locally, leading to more accurate and reliable results. The new methodology is applied to a benchmark off-grid community in Ghana. The results demonstrate that the use of gasifiers reduces the project cost notably (by 90%) driven by the reduced biomass cost, which can be supplemented by locally generated biomass from agricultural activities. In addition, this technology constitutes a clean source of energy, reducing the total CO2 emissions by 83% compared to a baseline case in which only diesel generators are used. Moreover, it is demonstrated that biomass gasification can effectively act as base load power generation technology to reliably cover most of the local demand, thereby enabling a clean and inexpensive dispatchable local power generation. Finally, a sensitivity analysis reveals that the economic feasibility of the plant is more sensitive to the biomass cost than the selling price of biochar, resulting in a 33% increment in the total project cost when the price of biomass increases from 0 to 0.4 $/kg. Nevertheless, gasification remains as the predominant power generation technology even under unfavorable prices.

Techno-economic analysis of small-scale ammonia production via sorption-enhanced gasification of biomass

Biomass gasification is a green and efficient pathway for lowering the carbon footprint of ammonia production. Decentralized, small-scale biomass gasification plants (<150 t NH3/day output) are more practical than large plants due to sustainable large-scale biomass supply constraints. Small-scale biomass gasification for ammonia production faces the challenges of high energy consumption and production costs. Process intensification through sorption-enhanced gasification (SEG) integrates steam gasification and in-situ CO2 separation using regenerable CaO sorbents, directly producing hydrogen-rich syngas (∼70 vol%), which streamlines syngas conditioning and increases cost-effectiveness. Two SEG process configurations for small-scale biomass-to-ammonia (∼45000 t of agricultural residues/year) were proposed: SEG process A, which produced low-carbon ammonia without air separation, and SEG process B, which employed an air separation unit to deliver carbon-negative ammonia by capturing CO2. The two processes were compared against a dual fluidized bed gasification (DFBG) process, which generated green ammonia without an air separation, like SEG process A. Of the three cases, SEG process B showed the lowest biomass (2.14 t biomass/t NH3) and water consumption (0.47 t H2O/t NH3) and avoided 2.8 t CO2/t NH3, making it carbon-negative. While the DFBG process and SEG process A had higher energy efficiencies, SEG process B posted the lowest net energy consumption (36.6 GJ/t NH3). Furthermore, SEG process B had the lowest ammonia production cost ($692/t NH3) and payback time (9.4 years), making it the most economically viable. Sensitivity analysis showed that favorable carbon credit policies could boost the economics of SEG process B to match large-scale plants.

Energy, Exergy, Exergoeconomic and Exergoenvironmental Modeling of a Proposed Multigeneration Power Plant

There is rising energy demand; yet, nonconventional fuels are yet to meet these demands. It has been established that fossil fuels contribute to global warming and climate change. How, then, do we use of fossils to power our lives and industries without endangering our environment and humanity? Here, comes integrated multigenerational power plant. A Multigeneration power plant system is an advanced and integrated approach that goes beyond cogeneration (Combined Heat and Power - CHP) by simultaneously producing multiple forms of energy from a single or double fuel source. In addition to generating electricity and useful heat, a multigeneration power plant can also produce cooling, desalination, or other valuable products or services. This innovative system maximizes the energy efficiency of the overall plant, utilizing the waste heat and by-products to provide additional functionalities. The present work is a proposed multigenerational power plant that comprises of a gas turbine, HRSG, steam turbine, a biomass gasification plant, solar PVT system, a PEM Electrcolyzer, VARS and a Kalina Cycle. The fuel input-output model is 2 X 5: natural gas and syngas from biomass gasification process, while outputting multiple sources of energy – electricity, heating, cooling, hydrogen production and drying. The whole integrated multigenerational power plant was modeled in Engineering Equation Solver (EES). The Net power is 51.404MW; Thermal efficiency 40.1%; exergy efficiency 62.02%; sustainability 1.39. Exergoeconomic assessment provided useful information to enhance the cost-effectiveness of the integrated multigenerational power plant system by evaluating each component separately. NO emission rates 0.04393 kg/s, CO emission 0.00934 kg/s, CO2 specific emission is 0.3364 kgCO2/MWh; all environmental indicators confirmed it is the most environmentally friendly option.

Techno-economic assessment of a novel integrated multigeneration system to synthesize e-methanol and green hydrogen in a carbon-neutral context

A novel and efficient multigeneration system aiming to achieve near-zero CO2 emissions is proposed. The system employs a methanol production process utilizing captured CO2 from the flue gas of a biomass-gasification plant. The proposed system successfully generates green H2 through water electrolysis, supported by thermal power, with a portion of the hydrogen reacting with CO2 to produce e-methanol. Additionally, the system produces other valuable products, including power, cooling, O2, and CO2, in a coherent manner, benefiting from a low-emission framework and exhibiting high thermodynamic performance. The proposed multigeneration system consists of a biomass-gasification-based power plant, a water electrolyzer, a methanol generation unit, a carbon capture unit, and a steam jet ejector-based refrigeration cycle. The integrated multigeneration system is analyzed from the energy, exergy, and economic aspects. The results demonstrate the system's ability to achieve production rates of 430.25 kg/h of e-methanol and 190 kg/h of green H2. Furthermore, the energy and exergy efficiencies of the system are found to be 78.13% and 71.63%, respectively. The CO2 emissions analysis reveals that the proposed system significantly reduced total CO2 emission to 78.5% (0.61 kgCO2/kg). The total cost of production is estimated to be 0.087 $/kg.

Design of an energy management system applied to an electric power plant based on a biomass gasifier

Biomass gasification plants for electricity generation are an environmentally friendly technology. One of their main problems is their poor responsiveness to load variations when the plant operates off-grid. For this reason, they are usually grid-connected systems.Therefore, as a solution, an energy management system that allows the plant to operate off-grid is proposed. The system has been obtained through the optimal design of unidirectional and bidirectional Z-source converters and their coupling with their series outputs. This approach has been applied to a biomass gasification power plant.To validate the system, the results of an experimental 10 kW gasification plant are presented. With the plant working off-grid, there is a sudden load increase of 2.5 kW, and due to the proposed system performance, there is only an output voltage oscillation of less than 1%, preserving a stable power supply.This proposed system allows the plant to work isolated or coupled to a weak micro-grid of renewable energies. Obtaining a permanent supply of quality and also improving its efficiency. Thus, the gasification technology can be used for electricity generation in isolated areas of many developing countries, where the electrical grid is not totally developed, but there are available biomass sources.

Some Perspectives for the Gasification Process in the Energy Transition World Scenario

Energy demand has increased over the years due to population growth, industrial, and socio-economic developments, cornerstones of human civilization. Additionally, climate change alarms are placing the energy transition in the top concerns of intergovernmental organizations. Therefore, there are several reasons for concern regarding the need for a new paradigm in the world energy scenario. This perspective article focuses on the contribution that the gasification process may have in the global energy transition scenario. The perspectives for a full world energy transition are that it cannot be accomplished without a transportation fuel transition and an industry transition. Biomass gasification is a sustainable process that allows the production of a large range of commodities such as electricity and heat, biofuels, and chemicals. Meanwhile, some challenges such as tar, impurities, and soot must be overcome or at least limited to an acceptable minimum to promote the economic viability of the gasification plants before they can effectively contribute to the world energy transition. In this regard, further research should be made focused on improving the syngas quality and the economic viability of a biomass gasification plant. This can be achieved by several means including new reactor designs, advanced gasification processes (e.g., plasma gasification and supercritical water gasification), and intensifying the gasification process.

POTENTIAL USE OF PALM OIL AND COCOA WASTE BIOMASSES AS SOURCES OF ENERGY GENERATION BY GASIFICATION SYSTEM IN THE STATE OF PARÁ, BRAZIL

Regional development in the state of Pará (Brazil) continues to be limited by lack of access to energy. This is a problem that is widespread in several rural communities and agricultural regions. Therefore, this study aimed to analyze the potential use of palm oil and cocoa processing waste biomass, which are abundant in the state and whose energy capacities can be used to generate electricity in biomass gasification plants. To do so, a literature review on elementary and calorific value analysis of palm oil (empty fruit bunches, fibers, kernel shell and cake, trunks, and others) and cocoa (pod husks) were conducted. The findings have shown that both waste biomass materials have satisfactory energetic characteristics for use in gasification plants. Thus, palm oil and cocoa processing waste biomasses are alternative energy sources for producers of these fruits in upstate Pará, enabling the development of the region.

Application of innovative methodology for risk assessment and inspection methods on example of small experimental biomass gasification unit

Application of Innovative methodology for risk assessment and inspection methods is the result of a long-term work in the field of Risk-Based Inspection. As such, it was successfully applied on oil and gas facilities in the Middle East. As an example of its versatility, application will be shown on small experimental biomass gasification plant utilized for the purpose of combined heat and power generation, built in Serbia in the middle of the past decade. Throughout the analysis both active and passive damage mechanisms will be identified as well as barriers thus enabling the creation of a system that documents the dynamics of the damage mechanisms and installed barriers.

A Decision-making Framework to Evaluate and Select Optimal Biomass Gasification Plant Size for Sustainable Regional Bioenergy Development

A Decision-making Framework to Evaluate and Select Optimal Biomass Gasification Plant Size for Sustainable Regional Bioenergy Development

TECHNICAL AND ECONOMIC ANALYSIS OF PRODUCING 250 KW POWER USING THE GASIFICATION SYSTEM AT THE VARIETY WOODS AND GREENHEART LIMITED SAWMILL IN GUYANA.

A technical and economic analysis was conducted on the viability of operating a 250 kW wood biomass gasification power plant to produce electricity for the sawmill at Variety Woods and Greenheart Ltd. in Guyana. The major economic cost factors considered in the gasification plant’s 20-year life comprised a wood chipper, pellet machine, gasification system and operation and maintenance cost. The researchers did a cash flow projection using a spreadsheet program to determine the net present value (NPV), internal rate of return (IRR), the payback period and the return on investment (ROI). The main cash inflow in the analysis is savings from diesel fuel import to power the current diesel power plant at the sawmill. The implementation of the wood biomass gasification plant will save the company US$ 99,600 annually. In the economic analysis, a sensitivity analysis was conducted by the researchers on the capital cost, which was the major factor affecting the economic assessment. In both scenarios, the economic analysis of the proposed gasification plant shows a positive NPV, which suggests an attractive investment financially. The IRR for case one was found to be 4.70% and for case 2 was 6%. For case 1, the gasification plant's return on investment is 13.3% and for case 2, it is 36.56%. The payback period for the wood biomass gasification system was 20 years 5 months for case 1 and for case 2 was observed to be 10 years 1 month.

The novel integration of biomass gasification plant to generate efficient power, and the waste recovery to generate cooling and freshwater: A demonstration of 4E analysis and multi-criteria optimization

It has long been understood that biomass energy may be utilized to transform chemical energy into electrical energy and is a renewable energy source. In this study, a unique combined cycle for generating reliable electricity from biomass chemical energy is presented and tested. In this regard, a new system is proposed based on a biomass gasifier using wood as inlet biomass and the gas turbine to utilize the synthesis gas. Also, the waste heat is recovered via a multi-effect desalination system, an absorption chiller, and a heat recovery steam generator (HRSG). The system is investigated from 4E analysis standpoints, and multi-objective optimization is conducted to seek the best solution for the proposed energy system. The results pinpoint that the compressor's pressure ratio, biomass moisture content, turbine inlet temperature (TIT), and biomass flow rate play a crucial role in the system's performance. Optimization results indicate that, at the optimal point, total exergy efficiency and pollutions are 28.32 % and 0.4797 kg / kWh, respectively.

Flexible Power and Biomass-To-Methanol Plants With Different Gasification Technologies

The competitiveness of biofuels may be increased by integrating biomass gasification plants with electrolysis units, which generate hydrogen to be combined with carbon-rich syngas. This option allows increasing the yield of the final product by retaining a higher amount of biogenic carbon and improving the resilience of the energy sector by favoring electric grid services and sector coupling. This article illustrates a techno-economic comparative analysis of three flexible power and biomass to methanol plants based on different gasification technologies: direct gasification, indirect gasification, and sorption-enhanced gasification. The design and operational criteria of each plant are conceived to operate both without green hydrogen addition (baseline mode) and with hydrogen addition (enhanced mode), following an intermittent use of the electrolysis system, which is turned on when the electricity price allows an economically viable hydrogen production. The methanol production plants include a gasification section, syngas cleaning, conditioning and compression section, methanol synthesis and purification, and heat recovery steam cycle to be flexibly operated. Due to the high oxygen demand in the gasifier, the direct gasification-based plant obtains a great advantage to be operated between a minimum load to satisfy the oxygen demand at high electricity prices and a maximum load to maximize methanol production at low electricity prices. This allows avoiding large oxygen storages with significant benefits for Capex and safety issues. The analysis reports specific fixed-capital investments between 1823 and 2048 €/kW of methanol output in the enhanced operation and LCOFs between 29.7 and 31.7 €/GJLHV. Economic advantages may be derived from a decrease in the electrolysis capital investment, especially for the direct gasification-based plants, which employ the greatest sized electrolyzer. Methanol breakeven selling prices range between 545 and 582 €/t with the 2019 reference Denmark electricity price curve and between 484 and 535 €/t with an assumed modified electricity price curve of a future energy mix with increased penetration of intermittent renewables.

Integrated management of mixed biomass for hydrogen production from gasification

In this study, we propose a novel optimization method for designing and operating various types of biomass-based renewable hydrogen production systems. To this end, we considered the coupling of multiple biomass hybrid utilization processes for hydrogen production. First, we calculated and evaluated the biomass utilization potential of a given area. Second, we predicted the biomass gasification products using chemical reaction kinetics and thermodynamic models. Finally, we determined the optimal annual total cost of the hydrogen production supply chain by optimizing the microscopic operation of the biomass gasification plant. Through the proposed method, it is possible to effectively conduct a comprehensive assessment of regional biomass material hydrogen production; moreover, the optimal design of the biomass hydrogen production supply chain can also be determined based on the availability of biomass and hydrogen demand. More precisely, the logistics operations under fluctuating demand conditions were realized, enabling strategic decision-making for planning a biomass hydrogen production system. To validate the model, a case study analysis of biomass hydrogen production, to be launched in Sichuan Province, China, is presented.

Simulations and experimental study to compare the behavior of a genset running on gasoline or syngas for small scale power generation

Syngas produced from small-scale biomass gasification plants (tens of kW) can generate power from biomass resources. However, due to the syngas gensets demand is marginal, compared to gasoline gensets, it is not easy to find a genset specially designed to run on syngas. In this paper, an experimental study of a genset running on two kinds of fuel has been carried out. The genset used is a 10 kW ICE initially designed to run on gasoline, in parallel, simulations based on CHEMKIN-PRO software were made. The study focuses on the comparison of the ICE operation independently working on gasoline and syngas. Modifications were required in the genset to adapt the intake system to run on syngas. The syngas is obtained from a gasifier. According to the test, it is possible to convert a gasoline engine to a 100% syngas engine through straightforward modifications in the inlet manifold but reducing the efficiency and power. The electrical power running the genset on gasoline was 6.7 kW, whereas, with syngas, it is 4.8 kW (31.4% of reduction). The efficiency running the ICE on gasoline was 13.7% at its rated power, whereas for the genset fuelled on syngas, it was 10.5% (23.4% reduction).

Potentials and Costs of various Renewable Gases: A Case Study for the Austrian Energy System by 2050

This analysis estimates the technically available potentials of renewable gases from anaerobic conversion and biomass gasification of organic waste materials, as well as power-to-gas (H2 and synthetic natural gas based on renewable electricity) for Austria, as well as their approximate energy production costs. Furthermore, it outlines a theoretical expansion scenario for plant erection aimed at fully using all technical potentials by 2050. The overall result, illustrated as a theoretical merit order, is a ranking of technologies and resources by their potential and cost, starting with the least expensive and ending with the most expensive. The findings point to a renewable methane potential of about 58 TWh per year by 2050. The highest potential originates from biomass gasification (~49 TWh per year), while anaerobic digestion (~6 TWh per year) and the power-to-gas of green CO2 from biogas upgrading (~3 TWh per year) demonstrate a much lower technical potential. To fully use these potentials, 870 biomass gasification plants, 259 anaerobic digesters, and 163 power-to-gas plants to be built by 2050 in the full expansion scenario. From the cost perspective, all technologies are expected to experience decreasing specific energy costs in the expansion scenario. This cost decrease is not significant for biomass gasification, at only about 0.1 €-cent/kWh, resulting in a cost range between 10.7 and 9.0 €-cent/kWh depending on the year and fuel. However, for anaerobic digestion, the cost decrease is significant, with a reduction from 7.9 to 5.6 €-cent/kWh. It is even more significant for power-to-gas, with a reduction from 10.8 to 5.1 €-cent/kWh between 2030 and 2050.

An integrated two-step process of reforming and adsorption using biochar for enhanced tar removal in syngas cleaning

Tar reforming processes conducted at typically high-temperatures for syngas cleaning using biochar in biomass gasification plants, fail to remove the thermally stable smaller aromatic compounds (such as naphthalene, indene, anthracene) thereby retaining the risk of clogging downstream equipment. In this context, integration of an additional step of adsorption at relatively lower temperature, targeting the lighter tar compounds is proposed. An integrated approach for removal of tar generated from mallee wood bio-oil, involving reforming at 750 °C and adsorption at 220 °C was systematicaly evaluated against conventional reforming process. The comparative assessment included tar analysis estimating tar yield and examining tar constituents through UV-fluorescence spectroscopy, biochar structural analysis based on Raman spectroscopy supported by reactivity studies through TGA, and biochar morphological analysis by FESEM imaging and BET analysis. Tar analysis reveals a drastic drop in the two-step process by ∼ 80%: with ∼ 60% tar reduction in reforming and ∼ 40 % of residual tar in adsorption. The removal of lower aromatics was confirmed through UV-fluorescence of residual tars. The Raman spectroscopy shows a growing predominance of higher and lower aromatics in catalyst and adsorbent respectively. These trends were explained based on cross-linking of aromatic compounds through a polymeric condensation in reforming and the penetration of light tars into the micropores in adsorption. The effects of aromaticity are reaffirmed in reactivity studies by TGA. The BET results show a manifold decrease in porosity, implying coverage of the pore surface by the adsorbing species, which is also evident in FESEM images.