Renewable Energy xxx (2016) 1e12 Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene Strategies for selection of thermo-chemical processes for the valorisation of biomass Rawel Singh a, b, Bhavya B Krishna a, b, Garima Mishra a, b, Jitendra Kumar a, Thallada Bhaskar a, b, * a b Thermo-catalytic Processes Area(TPA), Bio-Fuels Division (BFD), CSIR-Indian Institute of Petroleum (IIP), Dehradun 248005, India Academy of Scientific and Innovative Research (AcSIR), New Delhi, India a r t i c l e i n f o a b s t r a c t Article history: Received 10 January 2016 Received in revised form March 2016 Accepted March 2016 Available online xxx Research on biomass conversion has been gaining a lot of interest as biomass is renewable and sustainable in nature Products from biomass can be obtained by different methods amongst which thermochemical route has a very high potential Biomass is generally available in a localised manner in varying quantities and qualities throughout the year and hence, region specific technologies have to be developed considering the end user requirement Pyrolysis is a very versatile technique with the above considerations The process parameters can be tweaked to necessity to produce more bio-oil or bio-char Thermogravimetric analysis is essential for understanding the decomposition behaviour of the feedstock before the lab scale pyrolysis is carried out Pyrolysis using several regional feedstocks has been carried out under nitrogen and hydrogen atmosphere and different biomass feedstocks were also liquefied using sub/supercritical solvents This review aims to provide a comparison of the results obtained using various processes This helps in the decentralised processing of biomass (dry biomass using pyrolysis and wet biomass by hydrothermal liquefaction) to produce bio-crude which can be upgraded to produce fuels/ chemicals/petrochemical feedstocks in an environmental friendly manner © 2016 Elsevier Ltd All rights reserved Keywords: Pyrolysis Hydrothermal liquefaction Kinetic analysis Lignocellulosic biomass Aquatic biomass Algae Introduction Fossil resources derived fuels have played the most important role in the rapid technological progresses over the past few centuries It is estimated that more than 85% of the world's energy requirements are obtained from conventional fuels [1] Energy scenarios project that world's annual energy consumption will increase steeply from current value of 500 to 1000e1500 Exa Joules per annum by 2050 [2e4] Use of fuels derived from fossil resources leads to global warming due to high levels of CO2 emission in atmosphere Renewable, sustainable and environment friendly alternate resources are required to address these issues Solar radiation, winds, tides and biomass are renewable resources and while first three resources can be used to obtain energy, biomass can be used to produce energy, chemicals and materials [5] Need for a secure source of transportation fuels and chemicals make it essential to explore bio-fuels/bio-based hydrocarbons as * Corresponding author Thermo-catalytic Processes Area(TPA), Bio-Fuels Division (BFD), CSIR-Indian Institute of Petroleum (IIP), Dehradun 248005, India E-mail addresses: tbhaskar@iip.res.in, thalladab@yahoo.com (T Bhaskar) alternatives to hydrocarbons derived from fossil resources [6] The transition from the current fossil-based to bio-based carbon economy is expected to evolve continuously in the coming decades and a continuous changeover to more complex bio-renewable feedstocks like agricultural residues, industrial wastes, green plants, wood, or algae will occur [7] Types of biomass feedstocks Biomass is a plant matter of recent (no geologic) origin or material derived there from and can be used to produce various useful chemicals and fuels [8,9] Biomass contains variety of plant species with varying morphology and chemical composition Low hydrogen to carbon ratio and high oxygen to carbon ratio in biomass suggests that biomass can be utilised for the production of fuels as well as functional chemicals [7] Depending on the nature of biomass used different biomass generation are shown in Fig First-generation bio-fuels are derived from edible feedstock from the agricultural sector such as corn, wheat, sugarcane, and oilseeds First generation biofuels have limitation of food versus fuel issue Second-generation bio-fuels are non-edible and http://dx.doi.org/10.1016/j.renene.2016.03.023 0960-1481/© 2016 Elsevier Ltd All rights reserved Please cite this article in press as: R Singh, et al., Strategies for selection of thermo-chemical processes for the valorisation of biomass, Renewable Energy (2016), http://dx.doi.org/10.1016/j.renene.2016.03.023 R Singh et al / Renewable Energy xxx (2016) 1e12 Second generation biofuels First generation biofuels Edible parts of agricultural crops and forest trees Competes with human and animal food Third generation biofuels Fourth generation biofuels Non edible parts of crops, forest residues, energy crops Macro algae, micro algae Modified organisms for better yield No food vs fuel issue Does not compete with agricultural land Yet to be used in large scale Food production for human population is essential-hence availability of biomass is plenty Utilises CO2 from atmosphere or from industrial emissions for growth Food vs fuel issue Expected higher yield per hectare Fig Different biofuel generations depending on biomass type comprise of raw materials derived from lignocellulosic biomass and crop waste residues from various agricultural and forestry processes [10,11] Lignocellulosic biomass has three major components: cellulose, hemicellulose and lignin The agricultural residues can be classified as field and seed crop, fruit and nut crop, vegetable crop and nursery crop [12] The residues generated from the forest products industry can be divided into two categories: (1) logging residues-generated from logging operations, e.g., from final fellings and (2) industrial by-products- generated by the forest industries during processing of timber, plywood, particleboard, pulpwood, etc [13,14] Energy crops are specifically grown to produce some form of energy Energy crops are generally divided into two types: herbaceous and woody Herbaceous energy crops are mostly types of grasses, which are harvested like hay Perennial grasses, such as switchgrass, miscanthus, bluestem, elephant grass, and wheatgrass could all potentially be grown as energy crops [15] Third generation bio-fuels are based on algal matter (micro- and macro algae) and cyanobacteria, which yield carbohydrates, proteins, vegetable oils (lipids), and, subsequently, biodiesel and hydrogen gas, are gaining considerable interest The term algae can refer to microalgae, cyanobacteria (the so called “blue-green algae”), and macro algae (or seaweed) The differences between microalgae and macro algae are shown in Fig Thermochemical conversion of biomass There are several methods of conversion of biomass viz: mechanical, chemical, biochemical and thermochemical Mechanical processes only perform a size reduction of feedstock Chemical processes carry out a change in the chemical structure of the molecule by reacting with other substances These processes include the wide class of chemical reactions where a change in the molecular formula occurs [16] Bio-chemical processes occur at lower temperatures and most common types of biochemical processes are fermentation and anaerobic digestion The fermentation uses microorganisms and/or enzymes to convert a fermentable substrate into recoverable products (usually alcohols Fig Comparison of microalgae and macro algae or organic acids) [17] Anaerobic digestion involves the bacterial breakdown of biodegradable organic material in the absence of oxygen over a temperature range from about 30 to 65 C The main end product of these processes is biogas (a gas mixture made of methane, CO2 and other impurities) [16,18] An overview of thermochemical and biochemical processes during biorefinery is shown in Fig Thermochemicals processes are carried out in the presence of heat and can also use catalyst Thermo-chemical methods utilize the entire biomass without any pre-treatment steps to produce value added hydrocarbons In comparison to the biochemical processes, thermochemical processes occur faster in the range of few seconds, minutes or hours when the former takes time in the range of days to complete The other advantages of thermochemical methods of conversion are that they are not feedstock specific and can also process moisture-rich/aquatic feedstocks The micro-organisms are feed specific and even the slightest of change could lead to its non-functionality This poses a major risk in the commercialisation of the process at an Please cite this article in press as: R Singh, et al., Strategies for selection of thermo-chemical processes for the valorisation of biomass, Renewable Energy (2016), http://dx.doi.org/10.1016/j.renene.2016.03.023 R Singh et al / Renewable Energy xxx (2016) 1e12 Biomass Pre-treatment Holocellulose Fermented to ethanol, butanol, xylitol etc by biochemical routes Conversion to high value chemicals by thermochemical routes Lignin Only burnt in biochemical processes Thermo-chemical route can be used for the production of aromatics Fig Overview of thermochemical and biochemical processes for biomass conversion industrial level since the biomass availability in terms of quality and quantity keeps varying all through the year Various thermochemical processes for biomass conversion are shown in Fig This review article focuses on the strategies for selection of thermochemical processes for valorisation of diverse biomass feedstocks and need to have decentralised units that may be the most immediate solutions for introduction of bio-based energy systems For the implementation of these units most important thing is to the fundamental research on diversified feedstocks Combustion to know the thermal decomposition behaviour, kinetics of biomass and effective heat management through thermodynamic data Based on the fundamental studies from TG/DTG studies pyrolysis approaches for dry biomass have been proposed for centralised and decentralised biorefineries For effective utilisation of wet biomass hydrothermal liquefaction has been proposed and effect of various parameters has been discussed The utilisation of biomass components viz cellulose and lignin to valuable chemicals has also been discussed using appropriate catalytic and thermal methods Heat/ electricity Centralised heating, electricity by IGCC Syn gas FT to form fuels/ chemicals Gasification Steam reforming to hydrogen Biomass Upgraded to fuels/fuel blends Bio-oil Pyrolysis/ hydrothermal liquefaction Bio-char Upgraded to produce chemicals or petrochemical feedstocks Adsorbents, catalysts, electrodes, soil management and C-sequestration etc Fig Thermochemical processes for biomass conversion Please cite this article in press as: R Singh, et al., Strategies for selection of thermo-chemical processes for the valorisation of biomass, Renewable Energy (2016), http://dx.doi.org/10.1016/j.renene.2016.03.023 R Singh et al / Renewable Energy xxx (2016) 1e12 TG/DTG studies of different feedstocks “Thermogravimetric analysis” is a technique in which the mass of a substance is measured as a function of temperature, while the substance is subjected to a controlled temperature programme The thermal behaviour of biomass is determined using TGA The TG and derivative thermogravimetric (DTG) curves observed from TGA can be used to determine the apparent weight loss of samples Various thermodynamic parameters and kinetic studies of different feedstocks have been carried out and discussed below 4.1 Thermodynamic parameters Pyrolysis behaviour and kinetic study of different lignocellulosic biomass feedstocks (Cerus, Cheed, Cokad, Sagwan and Shimbal) have been done The thermodynamic properties were calculated using the kinetic triplet values determined using the model free approaches The results obtained from thermal decomposition processes indicate that there are three main stages in the pyrolysis, i.e., dehydration, active and passive pyrolysis The value of apparent activation energy calculated using isoconversional methods are used to evaluate the thermodynamic properties such as enthalpy, Gibbs free energy and entropy of biomass pyrolysis A shift in the DTG curve, i.e increase in the DTG peak temperature is observed as the heating rate increases, but this shift is not uniform for all the biomass studied The estimated thermodynamic parameter values are found to be different for biomasses all of which have forest as their origin; but they are similar for a particular biomass at different heating rates The model-free approach (Friedman method, Kissinger Akahira Sunose method and Flynn-Wall-Ozawa method) does not require assumption of specific reaction models, and yields unique kinetic parameters as a function of either conversion (isoconversional analysis) or temperature (non parametric kinetics) Model free kinetic methods are conversional in evaluation of pre-exponential factor and reaction mechanism and the constraints involved not permit a straight forward evaluation of the remaining kinetic parameters A and f(a) Thus a combination of pyrolysis data from TGA and model free (isoconversional) methods can be a potent tool for predicting the reaction kinetics as well as the thermodynamic parameters of the biomass pyrolysis process The results obtained from the TGA studies of the feedstocks showed that the apparent activation energy values calculated from the isoconversional methods (150e170 kJ/mol) are found to be similar for the all studied forest biomass except for Cokad which is showing a relative high value of Ea (~200 kJ/mol) The values of the pre-exponential factor are found to lie in the range of 108e1014 sÀ1 The value of A for Cokad is of the order of 1014 from which it can be attributed that the rotations of the active complex and the reagent not change during the reaction The reaction order values are found to be high which can be attributed to the multiscale and multiphase nature of biomass feedstock The estimated thermodynamic parameter values are found to be different for studied biomasses all of which have forest as their origin; but they are similar for a particular biomass at different heating rates 4.2 Kinetic studies and reaction mechanism during pyrolysis The thermal decomposition of biomass proceeds via a very complex set of competitive and concurrent reactions with formation of over a hundred intermediate products and thus the exact mechanism for biomass pyrolysis remains a mystery till date Modelling pyrolysis reactions with its unrevealed reaction mechanism presents a great challenge The specific temperatures at which various heterogeneous reactions occur, their reaction rates and the energies involved in these reactions are valuable information useful for pyrolysis system design The development of thermochemical processes for biomass conversion and proper equipment design requires the knowledge of several process features which include a good understanding of the governing pyrolysis mechanisms, the determination of the most significant pyrolysis parameters and of their effect on the process and knowledge of the kinetics [19] Understanding both multiscale and multiphase complexities represents a vital step forward in optimizing pyrolysis and developing next-generation biofuel technologies [20] A precise conception of solid state pyrolysis kinetics is very crucial in designing and operating industrial biomass conversion systems The kinetic modelling studies of biomass pyrolysis assists in analysis and optimization of reaction conditions, process parameters and adaption of pyrolysis systems to regionally differing surrounding conditions and diverse nature of biomass feedstock Kinetic studies form basis for development of a prototype model for energy provision to remote rural areas Fundamental research will lead to a ‘building-up’ approach whereby chemical mechanisms are integrated into particle models (accounting for transport phenomena) which are capable of predicting global performance (i.e., bio-oil yield and composition) Kinetics is the study of the dependence of the extent or rate of a chemical reaction on time and temperature Study of kinetics involves using mathematical models that quantify the relationship between the rate of reaction, time, and temperature [21] Kinetic analysis is expected to be capable of Revealing complexities in the reaction kinetics and prompting some mechanistic clues Adequately describing the temperature dependence of the overall reaction rate Producing reasonably consistent kinetic characteristics from isothermal and non isothermal data [22] A comprehensive kinetic analysis of a solid state reaction has four main stages: Stage 1: Experimental collection of data; Stage 2: Computation of kinetic characteristics for the data from stage 1; Stage 3: Validation of kinetic parameters estimated; Stage 4: Interpretation of the significance of any parameters evaluated in stage The different stages are shown in Fig Modeling of pyrolysis implies the representation of the chemical and physical phenomena constituting pyrolysis in a mathematical form The inherent complexity of the pyrolysis process has posed formidable challenges to modelling attempts The pyrolytic decomposition involves a complex series of interlinked reactions, and consequently, changes in the experimental heating conditions or sample composition and preparation may affect not only the rate of reaction, but also the actual course of reactions [21] Besides the sheer extent and range of pyrolysis reactions, several other issues complicate the modeling of pyrolysis More often these issues are inter-linked making it extremely difficult to separate the influence of one from another Modeling biomass pyrolysis is a challenge because of the variety of the raw materials involved and also because of the wide operating conditions Shin et al [23] observed that the accurate predictions of gas species and aromatics from the pyrolysis of biomasses, and mainly the effect of different operating conditions, not only require the description of the released components, but also the definition of their successive gas phase reactions The pyrolysis of various lignocellulosic materials is differentiated by the various reaction rates and the final product distribution achieved The quantitative formulation of the pyrolysis of a single biomass particle involving all the above-mentioned effects is a task requiring considerable effort [21] In view of the importance of Please cite this article in press as: R Singh, et al., Strategies for selection of thermo-chemical processes for the valorisation of biomass, Renewable Energy (2016), http://dx.doi.org/10.1016/j.renene.2016.03.023 R Singh et al / Renewable Energy xxx (2016) 1e12 Fig Different stages of kinetic analysis kinetics in pyrolysis of a biomass it is necessary to know the values of kinetic parameters of the biomass under a particular set of conditions However, difficulty arises in studying the thermal behaviour of biomass due to lack of exact knowledge of the course of reactions and their degree of completion Moreover, the vast number of products resulting from the thermal degradation of biomass hinders a thorough understanding of the process [21] Solid state reactions ordinarily demonstrate a tangled interplay of various chemical and physical processes such as solid-state decomposition, reaction of gaseous products with the solid, sublimation, polymorphous transitions, diffusion, melting, evaporation, adsorption, desorption, etc Therefore, the effective activation energy of a solid state reaction is generally a composite value determined by the activation energies of various processes and by their influence on the overall reaction rate Even if the temperature is kept constant (single isothermal experiment), the relative contributions of the elementary steps into the overall reaction rate vary with the extent of conversion ultimately resulting in a dependence of the effective activation energy on the extent of conversion Additionally, the kinetics of solid state reactions are known to be sensitive to pressure, size of crystals, gaseous atmosphere and many other factors which are likely to change during the process [24] The relative importance of the internal heat transfer to the external heat transfer is defined by the ratio of their respective characteristic times: tinternal hL ¼ Bi ¼ k texternal This is the definition of the Biot number, a dimensionless number commonly used in thermal analysis Biot numbers larger than 10 characterise a heat transfer limited by the internal conduction The internal pyrolysis number gives a measure of the relative importance of the internal conduction and the chemical reaction Py ¼ k AeÀE=RT rCP L2 The external pyrolysis number is the product of biot number and the internal pyrolysis number It gives the ratio between heat convection rate and chemical reaction rate and can be stated as follows, Py0 ¼ h AeÀE=RT rCP L Different solid state kinetic methods used for biomass pyrolysis are shown in Fig Studies of the kinetics of cellulose, hemicellulose and lignin separately revealed that the interactions between fractions are important, and the pyrolysis behaviour of biomass components is not completely additive like that in consecutive reaction model In the TG-DTG analysis of lignocellulosic material two or three peaks usually appear, that can be assigned to cellulose, lignin and hemicellulose, indicating that, although there are interactions between fractions, their identity is maintained Specific conclusions with respect to each feedstock are as follows [25,26]: Microcrystalline Cellulose: The master plots method predicts Please cite this article in press as: R Singh, et al., Strategies for selection of thermo-chemical processes for the valorisation of biomass, Renewable Energy (2016), http://dx.doi.org/10.1016/j.renene.2016.03.023 R Singh et al / Renewable Energy xxx (2016) 1e12 Fig Different solid state kinetic methods the pyrolysis process of microcrystalline cellulose by an autocatalytic reaction mechanism Friedman method gave more stable values than in comparison with Vyazovkin AIC method Distributed activation energy model gave a good fit to the kinetic data Lignin: The present work shows that lignin pyrolysis is a complex process and series of reactions occur rather than a simple single step reaction The lignin pyrolysis takes place over a wide range of temperature where three or more peaks can be seen in the DTG curve indicating presence of more than one pseudo components (sinapyl alcohol, coniferyl alcohol and guaiacyl alcohol) A wide distribution of activation energy in DAE Model shows presence of complex process with multiple reactions Rice Straw: The kinetic results for rice straw showed that the reaction mechanism for rice straw pyrolysis can be kinetically characterized by two successive reactions At conversion values less than 0.3 the decomposition of rice straw is governed by diffusion and it tends to third order rate equation at high conversion (predicted by compensation effect method) Groundnut husk: The kinetic results for groundnut husk present a complicated analysis, as at conversion values less than 0.1 the decomposition process is governed by diffusion but no clarity in mechanism is seen at conversion values greater than 0.1 Pine: In the case of pyrolysis process of pine wood at conversion values less than 0.7 the pyrolysis process is governed by two and three dimensional diffusion whereas at higher conversion values (a > 0.7) the mechanism is controlled by reaction order mechanism with order of reaction as 1.5 Deodar: Kinetic predictions similar to pine wood were observed in case of deodar pyrolysis showing that at conversion values less than 0.8 the pyrolysis process is governed by two dimensional diffusion whereas at higher conversion values (a > 0.8) the mechanism is controlled by a third order reaction mechanism The entire process for both pine and deodar wood pyrolysis is closer to diffusion controlled mechanism Water hyacinth: Water hyacinth presented a complex pyrolysis kinetics which could not be easily modelled The model free kinetic methods gave a bad fit for the case of water hyacinth showing its complicated pyrolysis behaviour DAE Model for three pseudocomponents used for this case gave a reasonable fit but the model could not be validated at higher heating rates Hence, more complex DAE Models with more number of pseudocomponents can be used further for study of kinetics of water hyacinth In addition to these feedstocks, kinetics of tamarind seed husk, another Indian biomass feedstock was studied Tamarind seed husk exhibited an abnormal behaviour giving very high activation energy values ranging from 144.53 to 639.57 kJ/mol with the model free kinetic analysis methods Model fitting and model free methods both suffer from certain drawbacks and have certain advantages over the other A combination of model free and model fitting kinetic methods can help in providing much more informative and meaningful results rather than empirical values with no mechanistic meaning Model free kinetic methods can be used efficiently to give initial parameter estimates for modelling biomass pyrolysis using distributed activation energy models It can be used to give preliminary insights into the kinetic triplet and to provide initial estimates for kinetic parameters which will help to avoid the extra computation time needed in optimization of objective function for prediction of these Please cite this article in press as: R Singh, et al., Strategies for selection of thermo-chemical processes for the valorisation of biomass, Renewable Energy (2016), http://dx.doi.org/10.1016/j.renene.2016.03.023 R Singh et al / Renewable Energy xxx (2016) 1e12 values Thus a combination of both these kinetic analysis methods can be a powerful tool for predicting the reaction kinetics of biomass pyrolysis process For effective valorisation of lignocellulosic biomass into energy products/chemicals, the study of role of solid catalyst is essential In this direction, the kinetic studies for selected feedstocks (rice straw, groundnut, pine, deodar) using the conventional microporous catalytic materials (such as Mordenite, y-zeolite, ZSM-5) has been initiated Pyrolysis of different feedstocks Pyrolysis is said to be the basis of all thermochemical methods of conversion and it is defined as the heating of any material in the absence of oxygen Pyrolysis processes produces bio-oil, bio-char and non-condensable gases as products and the amount produced varies on several factors The operating parameters for pyrolysis depend on the process type and the end product requirements Researchers have established the effect of pyrolysis temperatures, particle size, gas flow rate and many other parameters through their studies for the selected feedstock The process parameters have been identified in each case and the products have been characterised The end product utilisation is different in each case and this dictates the development of indigenous technologies depending on availability and costs involved with logistics Bio-oil obtained from slow pyrolysis of biomass does not have any direct high commercial value Hydropyrolysis experiments have been carried out by various groups and some of the parameters that have been tested are the effect of variations in final temperature, gas used, pressure, heating rate, and particle size Various reactor configurations have been used, which give us information on the heat and mass transfer effects There are conceptual articles which give us an insight into the possibilities of using hydropyrolysis in the transition stage of shifting from fossil-based economy to renewable feedstock-based economy Basic fundamental data has to be generated for both the processes using several feedstocks available in the presence and absence of catalysts thereby generating a huge database of information which will be helpful to understand the process No single process can produce solutions to all fossil resource utilisation problems and hence, different processes have to be used on different feedstocks to get different products 5.1 Types of pyrolysis There are various kinds of pyrolysis depending on the reactor employed, gas atmosphere used and residence time inside the reactor The classification of pyrolysis based on the residence time generally is slow, intermediate, fast and flash pyrolysis Pyrolysis is generally carried out in inert atmosphere like helium or nitrogen etc and in cases where hydrogen atmosphere is used the process is termed as hydropyrolysis It can also be carried out under vacuum Based on the reactor used, the pyrolysis processes are ablative, rotating cone, screw, auger, bubbling fluidised bed or circulating fluidised bed and microwave pyrolysis The products and ratios in which they are formed vary depending upon the reaction parameters such as environment, reactor used, pyrolysis temperature, rate of heating and source of heat Longer vapour residence time favours the production of bio-char Moderate temperatures and short vapour residence time are optimum for producing liquids One of the most important parameters in pyrolysis is the residence time of the solid phase which can vary from seconds to days Fast pyrolysis is characterised by high heating rates and short residence times Fast pyrolysis generally requires the feedstock to be supplied as fine particles; and the reactor design must facilitate rapid removal of the hot vapours from the presence of the hot solids In fast pyrolysis, liquid fuel called bio-oil condenses from the vapours and aerosols; the process also yields non-condensable gases of medium calorific value Other pyrolysis techniques include intermediate pyrolysis and flash pyrolysis In intermediate pyrolysis, reaction occurs at controlled heating rates thus avoiding tar formation Interestingly, the size and shape of the feed particles are less critical than in fast pyrolysis, which allows a wider variety of biomass feedstock Flash pyrolysis occurs with very fast heating rates of !1000 C/s and uses even shorter solid residence times ([...]... in-situ reaction monitoring studies For the development of efficient biorefineries, a detailed study on the available quantity and quality of feedstocks and processes/ combination of processes suitable for the same have to be identified in Indian scenario Detailed understanding of the chemistry and chemical engineering of the processes is required to make the commercialisation of the developed process a success... plants In case of heterogeneous catalysts, the catalyst should not deactivate easily due to the formation of coke With respect to the conversion methods, effective heat and mass transfer is required for the proper conversion of feedstock into the desired products The hydrothermal upgradation technology has immense potential for effective utilization of biomass functionality for the production of valuable... establish the reaction chemistry of pyrolysis process Knowledge of synergistic interactions between the main biomass components and the effect of their interactions on quantitative and qualitative yield of products needs to be given importance in the future works The significance of TGA to quantitatively resolve complex mixtures because of the characteristic thermal decomposition temperature of each component... out The detailed reaction mechanism for both the processes is still not known and yet to be understood As the reaction mechanism is different at different conditions, the reaction conditions can be modified to obtain the required product slate with increased yield and selectivity The identification of set generation of this data is essential for various feedstocks available The differences in the set of. .. to improve the further works on kinetic study at batch or continuous scales Further improvements in kinetic models and the modeling strategies need to be made to incorporate study of some complex biomass feedstocks and analyse their pyrolytic behaviour Kinetics for catalytic pyrolysis of lignocellulosic biomass is crucial in getting an insight into the pyrolysis behaviour of lignocellulosic biomass and... special reactor and separator designs for development of continuous processes and the capital investments needed for fullscale plants The current size of continuous systems available is not adequate for demonstration scale of operation It is also essential to understand the detailed chemistry and mechanism of HTL during continuous process There are a number of other critical issues hindering commercialization... kinetic studies for catalytic pyrolysis process need to be implemented The works carried out on slow and hydro pyrolysis are preliminary results and are a basis to understand the two processes The effect of operating parameters on the processes has been understood and certain process parameters have been optimised Detailed design for the fabrication of continuous reactors for both the processes has to... be extended further to a batch scale reactor or a fluidized bed reactor to examine if the predictions made by this study can be validated for a scaled up process The use of new experimental techniques capable of providing molecular-level insight is needed to improve upon existing global kinetic schemes Further efforts have to be made to deduce the reaction mechanism for the process of biomass pyrolysis... global scenario Hydrothermal liquefaction is a promising process for the valorisation of biomass, especially high moisture biomass Such biomass with high water content may be directly utilized without energy-intensive pretreatment and converted into bio-oil and platform chemicals The hydrothermal liquefaction of carbohydrates (cellulose and hemicelluloses) generally leads to a mixture of water soluble... products include acetic acid, formic acid, lactic acid, levullinic acid, 5-hydroxymethyl-2furaldehyde and 2-furaldehyde etc While hydrothermal technologies have many advantages over other thermochemical conversion routes of processing biomass, the fact remains that these technologies are not being widely commercialized today Part of this is due to the high pressures needed for processing which requires