PROCESS FOR THE PRODUCTION OF SYNTHETIC HYDROCARBONS FROM BIOMASS.

Abstract

A process for preparing synthetic hydrocarbons from biomass feedstock is provided. The process involves electrolysis of water in an electrolyzer to produce oxygen and hydrogen, use of the generated oxygen to gasify biomass feedstock under partial oxidation reaction conditions to generate hydrogen-poor syngas, and addition of at least a fraction of the generated hydrogen to the hydrogen-poor syngas to form hydrogen-rich syngas, which is reacted in a Fischer-Tropsch reactor to produce the synthetic hydrocarbons and water. At least a fraction of the water produced in the Fischer-Tropsch reaction is recycled in the electrolysis stage; optionally, the heat generated in the Fischer-Tropsch reaction is used to dry the biomass feedstock.

Description

SYNTHETIC HYDROCARBON PRODUCTION PROCESS FROM BIOMASS FIELD OF INVENTION The present invention relates to the field of the production of synthetic hydrocarbons from renewable and / or low-carbon sources. BACKGROUND OF THE INVENTION Carbon-based fossil fuels, such as coal, oil, and natural gas, are non-renewable and finite resources. Burning fossil fuels has caused an increase in atmospheric carbon dioxide concentrations, which could contribute to global climate change. Concern about carbon emissions from fossil fuels has created greater interest in developing synthetic fuel sources. Biofuels are considered viable alternatives to fossil fuels for several reasons, one of which is that they are renewable energy sources produced from biomass. One of the advantages of biomass fuel technology is that it offers the possibility not only of formulating a fuel-intensive product with a lower carbon content, but also of utilizing residual biomass materials, such as forestry byproducts, construction waste, and other wood waste products, human waste products, or agricultural raw materials, byproducts, and waste products. The Fischer-Tropsch (FT) process allows the conversion of hydrogen and carbon monoxide (commonly known as "singas") into liquid hydrocarbons, some examples of which include synthetic diesel, naphtha, kerosene, jet fuel, and paraffin wax. For an efficient Fischer-Tropsch reaction, the molar ratio of H₂:CO in the singas should be approximately 2:1. Various biomass-to-liquid conversion processes have been developed that involve the thermal gasification of biomass to generate syngas and use it in the Fischer-Tropsch reaction. As is well known in the art, biomass gasification produces hydrogen-poor syngas, with an H2:CO molar ratio of approximately 1:1. As a result, biomass-to-liquid conversion processes in which the Fischer-Tropsch reaction occurs require the incorporation of a water-gas swap (WGS) reaction or the generation of separate streams of hydrogen-rich syngas by using gas / methane reformers, such as a steam methane reformer (SMR) and / or an autothermal reformer (ATR), to supplement the hydrogen-poor syngas. Historically, the water-gas conversion process has been used, but this process is extremely time-consuming and expensive. The water-gas conversion reaction involves exchanging CO for CO2 to create hydrogen-rich syngas. This entails adding steam to hydrogen-poor syngas, where the steam reacts with carbon monoxide to produce carbon dioxide and hydrogen. Therefore, the water-gas conversion reaction requires heat and generates undesirable CO2. Natural gas reforming using a steam methane reformer and / or autothermal reformer also requires increased heat to produce combustion of natural gas, a non-renewable resource. ct7nccn / 77n7 / q / uιλι A biomass-to-liquid (BTL) conversion process, such as that disclosed in WO2012106795, incorporates biomass gasification and natural gas reforming to obtain liquid hydrocarbon products with lower carbon intensity (Cl) than petroleum fuels (a reduction of more than 40%). However, this process also relies on non-renewable feedstocks (i.e., natural gas). The integration of biomass gasification and water electrolysis has enabled hydrogen production. Water electrolysis supplies oxygen to a biomass gasifier, and the hydrogen side stream supplements the pure hydrogen stream from the gasifier. The process involves a water-gas exchange reaction, converting hydrogen-poor syngas from the gasifier into hydrogen-rich syngas. This process generates CO2, which is released into the atmosphere (International Journal of Hydrogen Energy 34 (2009) 772-782). This article also concludes that using electrolysis for hydrogen production is not economical. The integration of biomass gasification and water electrolysis to generate hydrogen-rich syngas was presented by McKellar et al. at the International Mechanical Engineering Congress and Exposition, held from October 31 to November 6, 2008. The process described in this paper involves the application of high-temperature steam hydrolysis to produce oxygen and hydrogen, and biomass gasification to obtain hydrogen-poor syngas. The overall process is quite complex, as it utilizes process heat from a biomass gasifier to enhance the efficiency of the steam electrolysis process. This paper also reports that the process yield can vary considerably depending on the biomass feedstock and the gasifier temperature, and that efforts to increase yield result in increased CO2 production. Furthermore, there is a need for an improved, low-carbon process for converting biomass into liquid for the production of synthesized hydrocarbons, which does not depend on non-renewable raw materials and in which renewable and / or low-carbon energy can be used to produce oxygen for biomass oxidation and which produces hydrogen to complement the hydrogen-poor syngas obtained from biomass. This background information is provided for the purpose of disclosing information that the applicant considers potentially relevant to the present invention. It does not necessarily imply, and should not be interpreted as, prior art that contradicts the present invention. BRIEF DESCRIPTION OF THE INVENTION One of the objectives of the present invention is to provide a process for producing synthetic hydrocarbons from renewable and / or low-carbon sources. According to one aspect of the present invention, a process for preparing synthetic hydrocarbons from biomass feedstock is provided, which comprises: a) electrolysis of water in an electrolyzer to produce oxygen and hydrogen; cbnccn / 77n7 / q / uιλι b) feeding the O2 generated in stage a) and the biomass feedstock to a gasifier, and gasifying the feedstock under partial oxidation reaction conditions to generate hydrogen-poor syngas with an H2:CO ratio of approximately 1:1; c) addition of at least a fraction of the H2 generated in step a) to the hydrogen-poor syngas generated in step b) to formulate hydrogen-rich syngas with an HzOO ratio of approximately 2:1; d) reaction of hydrogen-rich syngas in a Fischer-Tropsch reactor to produce synthetic hydrocarbons and water; e) recycling at least a fraction of the water produced in stage d) for use in stage a). BRIEF DESCRIPTION OF THE FIGURES The present invention will now be described by means of an exemplary embodiment, referring to the accompanying simplified flowcharts. In the figures: Figure 1 describes an organizational chart of a conventional biomass-to-liquid conversion process. Figure 2 describes an organizational chart of a biomass-to-liquid conversion process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION Unless otherwise defined, all technical and scientific terms used herein have the same meaning as they are commonly understood by a person skilled in the art to which this invention pertains. In this document, the term “singas” corresponds to an abbreviation of the English expression “synthesis gas”, which is a mixture comprising hydrogen, carbon monoxide and some carbon dioxide. In this document, the term “hydrogen-poor singas” refers to singas with a molar ratio of FeOOS of approximately 1:1, such as 0.5:1 to 1.2:1. In this document, the term “hydrogen-rich singas” refers to singas with an H2:CO molar ratio of approximately 2:1, such as 1.8:1 to 2.2:1, which is an optimal ratio recommended for use in the Fischer-Tropsch reaction. In this document, the term “electrolysis” refers to the process of using electricity to break down water into hydrogen and oxygen. In this document, the term “approximately” refers to a variation of ±10% of the face value. It is understood that this variation is always included in any given value provided herein, whether or not it is specifically mentioned. The present invention relates to a process for producing synthetic hydrocarbons from low-carbon and / or renewable sources (i.e., biomass, water, and electricity). This application allows for an improved biomass-to-liquid conversion process for the preparation of synthetic hydrocarbons, in which low-carbon and / or renewable energy is used to produce oxygen and hydrogen, where the oxygen is used in the efficient operation of the biomass gasifier, and the hydrogen is used in the production of tar-free hydrogen-rich syngas suitable for use in Fischer-Tropsch (FT) conversions to obtain synthetic hydrocarbons, including fuels for transportation. The inventors of the present invention discovered that integrating electrolysis, biomass gasification, and the Fischer-Tropsch reaction in the production of synthetic hydrocarbons produces almost stoichiometric conditions, where virtually all the hydrogen and oxygen generated through electrolysis is efficiently consumed in the process. Furthermore, recycling the water generated in the Fischer-Tropsch reaction, along with optionally recycling excess heat from the Fischer-Tropsch reactor and optionally recycling excess heat from the electrolyzer and gasifier and / or recycling refinery gas in the process, interestingly, allows for a process with minimal carbon emissions and that is economically viable, despite the seemingly high consumption of electrical energy. The process in this application does not include the water-gas exchange reaction or natural gas reforming, thereby reducing the carbon footprint and dependence on non-renewable raw materials (e.g., natural gas). Low-carbon renewable electricity from hydroelectric, solar, or wind sources (which is abundant and inexpensive in many regions) or low-carbon nuclear electricity can be used to eliminate the need for a non-renewable source such as natural gas. The process of the present invention involves the electrolysis of water in an electrolyzer to produce oxygen and hydrogen. The oxygen generated through the water electrolysis is used in the partial oxidation of biomass feedstock in a gasifier to generate hydrogen-poor syngas. At least a fraction of the hydrogen generated through the water electrolysis is added to the hydrogen-poor syngas to form hydrogen-rich syngas, which is subsequently reacted in a Fischer-Tropsch reactor to produce synthetic hydrocarbons and water. The water generated during the Fischer-Tropsch reaction is recycled in the electrolysis stage, thereby reducing or minimizing the amount of water required from an external source; finally, the recycled water is used as the primary source for the electrolysis process. Any suitable electrolyzer can be selected for the electrolysis stage. An appropriate temperature and / or pressure is selected for electrolysis according to the type of electrolyzer used. In some embodiments, the electrolysis stage can be carried out at a temperature of approximately 25 °C to approximately 1000 °C. In some embodiments, the electrolysis stage is carried out at a temperature of approximately 50 °C to approximately 850 °C. In some embodiments, the electrolysis stage is carried out at a temperature of approximately 75 °C to approximately 100 °C. In some models, the electrolysis stage can be carried out at a pressure of up to 50 bar. In some embodiments, the process involves removing excess moisture from the biomass feedstock to achieve the desired water content level before feeding it into the gasifier. Excess moisture from the biomass feedstock can be removed by subjecting the initial feedstock to a biomass dryer. The Fischer-Tropsch reaction is a highly exothermic reaction. At least a fraction of the energy or heat generated by the Fischer-Tropsch reaction, usually in the form of steam, is used in the process described herein to remove excess moisture from the biomass feedstock and, optionally, to generate power or electricity. In some forms, the process involves feeding at least a fraction of the steam generated during the Fischer-Tropsch reaction to recover heat, which is then used to remove excess moisture from the biomass feedstock. In some forms, the process involves feeding at least a fraction of the steam generated during the Fischer-Tropsch reaction to an electric generator to produce electricity, which can supplement the electricity from the electrolyzer; the residual heat resulting from power generation allows the removal of excess moisture from the biomass raw material. In some configurations, the refinery gas generated during the Fischer-Tropsch reaction is recycled in the biomass dryer to remove excess moisture from the biomass feedstock. As is well known in the field, electrolytic processes generate heat, which can be recovered. In some embodiments, the process involves recycling at least a fraction of the heat generated during the electrolysis stage to remove excess moisture from the biomass feedstock. In some embodiments, a fraction of the heat generated during the electrolysis stage can be used to generate energy for the electrolyzer. The waste heat from the electrolysis stage can be captured through Organic Rankine Cycle (ORC) technology and / or Sterling cycle generator. Biomass gasification produces hot raw gas, which can be fed to a steam-generating heat exchanger to produce steam and cooled raw gas. In some versions, the process includes using the steam generated in the heat exchanger to produce electricity to operate the electrolyzer, thus reducing the amount of electricity drawn from an external source. In some forms, the process also includes recycling or using at least a fraction of the excess heat generated during the gasification stage to remove excess moisture from the biomass raw material. The synthesized hydrocarbons, formulated through the Fischer-Tropsch reaction, can be fractionated to obtain a desired product, such as naphtha, diesel, jet fuel, etc. In some models, the refinery gas generated during the fractionation process is recycled in the biomass dryer to remove excess moisture from the biomass feedstock. In some forms, the heat generated by the Fischer-Tropsch reaction, the heat generated by the gasification reaction, and the refinery gas generated during the Fischer reaction cbnccn / 77n7 / q / uli Tropsch and / or the fractionation process are recycled in the biomass dryer to remove excess moisture from the biomass feedstock. In some configurations, the refinery gas generated by the Fischer-Tropsch reaction and / or the fractionation process can be used in an internal combustion engine or a microturbine to generate power for the electrolyzer. The waste heat from the internal combustion engine can be captured using organic Rankine cycle technology. In some configurations, the hydrogen-poor singas obtained from the gasifier undergoes one or more cleaning operations before being used in the Fischer-Tropsch reaction to remove contaminants such as tar, nitrogen compounds (NH3, HCN, etc.), sulfur compounds (H2S, COS, etc.), hydrogen halides (HCl, HF, etc.), and trace metals (Na, K, etc.). These cleaning operations involve the use of purification and protection units, which are well-known to those skilled in the art, to produce relatively clean singas suitable for use in a Fischer-Tropsch unit. In some embodiments, the raw, hydrogen-poor syngas, obtained directly from the gasification of biomass feedstock or after the cleaning operation, undergoes a carbon dioxide removal process before the reaction in the Fischer-Tropsch reactor. In some embodiments, the separated carbon dioxide is fed to the gasifier as a shielding or sealing gas to prevent air ingress. Synthetic hydrocarbons from the Fischer-Tropsch reaction can undergo one or more hydroprocessing operations to further optimize the products. These hydroprocessing operations include processes such as hydrocracking, thermocracking, hydrotreating, isomerization, or combinations thereof. In some configurations, a fraction of the hydrogen generated in the electrolysis stage is fed into the hydroprocessing operation. The hydrocarbons recovered from the hydroprocessing operation(s) can be further fractionated to obtain products such as naphtha, diesel, kerosene, jet fuel, lubricating oil, and wax. The combined unit comprising a hydroprocessor and a hydrocarbon fractionator is commonly known as a “hydrocarbon upgrader.” As those versed in the field know, there are several hydrocarbon treatment methods that can be incorporated into an upgrader unit depending on the desired refined products, which are essentially sulfur-free. The resulting diesel can be used to produce sulfur-free, environmentally friendly fuel and / or as a base for fuel blends, either used as is or blended with higher-sulfur fuels produced from petroleum sources. Exhaust gases generated during hydroprocessing operations can be used for power generation. A suitable biomass feedstock for the process of the present invention includes, among others, municipal waste, lignary waste, forest waste material, wastewater biomass, municipal sediment, cultivated biomass such as needle grass, cattails and fast-rotating crops, sewage biomass, agricultural waste (crop residues, livestock by-products, etc.), agricultural by-products, industrial fibrous material, harvested fibrous material or any mixture thereof. The process of the present invention may incorporate any gasifier known in the related art, such as those disclosed in U.S. Patent No. 7,776,114. Preferably, the process of the present invention involves the use of the gasifier described in the applicant's PCT publication No. WO 2018 / 058252, which is incorporated herein in full by reference. Some examples of suitable Fischer-Tropsch reactors include fixed-bed reactors and sludge bubble reactors, such as tubular reactors, and multiphase reactors with a stationary catalyst phase. In this document, the term “hydrocracking” refers to the splitting of an organic molecule and the addition of hydrogen to the resulting molecular fragments to obtain various smaller hydrocarbons (e.g., C10H22 + H2 → CH10 and structural isomers + CeHu). Because a hydrocracking catalyst can be active in hydroisomerization, structural isomerization can occur during the hydrocracking step. Isomers of the smaller hydrocarbons can also be formed.Preferably, the hydrocracking of a hydrocarbon stream derived from Fischer-Tropsch synthesis occurs through a hydrocracking catalyst, comprising a noble metal or at least a base metal, such as cobalt, platinum, cobalt-molybdenum, cobalt-tungsten, nickel-molybdenum, or nickel-tungsten, at a temperature of approximately 288 °C to approximately 400 °C (from approximately 550 °F to approximately 750 °F) and a hydrogen partial pressure of approximately 500 psia to approximately 1500 psia (from approximately 3400 kPa to approximately 10400 kPa). To better understand the invention described herein, the following examples are provided. It is understood that these examples are intended to describe illustrative embodiments of the invention and should not in any way limit the scope of the invention. EXAMPLES EXAMPLE 1: Figure 1 shows a process flowchart of a prior art biomass gasification circuit. Generally, the process is denoted by the number 10 and begins with a biomass feedstock (12). The biomass is then treated in a gasifier (14) to which the necessary oxygen (16) is fed. As is known, the gasifier generates a hydrogen-poor or hydrogen-deficient synthesis gas (singas) (18) with a molar ratio of FkCo of approximately 1:1, which is optionally subjected to cleaning operations (20) with the subsequent water-gas exchange reaction in unit (22) to obtain hydrogen-rich syngas (24) and carbon dioxide (26), which is either vented to the atmosphere or collected. The hydrogen-rich syngas (24) is then transferred to a Fischer-Tropsch reactor (28) to produce Fischer-Tropsch hydrocarbons or liquids (30) and water (32). The resulting hydrocarbons then proceed to a hydrocarbon cracking stage (not shown in the image) to obtain the desired hydrocarbon products, such as naphtha, diesel, etc. The diesel produced in this process is commonly known as synthetic diesel. Furthermore, the Fischer-Tropsch unit (not shown in the figure) and the hydrocarbon cracking unit are supplemented with an external hydrogen source. EXAMPLE 2: Figure 2 depicts a flowchart of one embodiment of the process of the present invention. Generally, the process is denoted by the number 100 and begins with the electrolysis of water (112) in the water electrolyzer (114) to generate oxygen (116) and hydrogen (118). A biomass feedstock (120) is then fed to a biomass dryer (124) to remove excess moisture and obtain a drier biomass feedstock (126) with a water content of approximately 15%. The biomass feedstock (126) and the oxygen (116) are then fed to a gasifier (128), and the feedstock is gasified under partial oxidation conditions to generate hydrogen-poor syngas (130) with a molar ratio of HsiCO3 of approximately 1:1. Optionally, the hydrogen-poor syngas (130) is subjected to cleaning operations (132) and / or a carbon dioxide removal operation (134) to remove CO2 (135).Optionally, CO2 (135) is fed to the gasifier (128) for use as a shielding or sealing gas. At least a fraction of the hydrogen (118) generated through the electrolysis of water (114) is added to the hydrogen-poor syngas (130) after cleaning operations via a pipeline (133) and / or after a carbon dioxide removal operation via another pipeline (136) to obtain hydrogen-rich syngas (137). This syngas is then reacted in a Fischer-Tropsch reactor (138) to produce hydrocarbons (140) and water (142). The hydrocarbons (140) are then subjected to one or more hydroprocessing operations (144), which precede the fractionation of the product (146) to obtain the desired hydrocarbon products, such as naphtha, diesel, etc. The water (142) is recycled in the electrolyzer (114) and subsequently used as the primary water source for electrolysis. Then, the energy or heat generated in the Fischer-Tropsch reactor (138), normally in the form of steam (162) from the Fischer-Tropsch reactor, is used to remove excess moisture from the biomass feedstock and / or generate electricity for the electrolyzer. The steam (162) passes through a heat exchanger (156) to recover heat, which is directed through a pipe (160) to the biomass dryer (124) to supplement the heat used in the excess moisture. Alternatively, the steam from the Fischer-Tropsch reactor (138) is directed through a pipe (162) to a power generator (152) to produce electricity (154) to supplement the electricity from the electrolyzer (114), and a fraction of the residual steam resulting from power generation passes through the heat exchanger (156) to obtain waste heat, which is directed through a pipe (160) to the biomass dryer (124) to supplement the heat used in the process of removing excess moisture, and the recovered water, which is directed through a pipe (168) to the water electrolyzer (114). cbnccn / 77n7 / q / uιλι Optionally, at least a fraction of the heat generated during the electrolysis process is directed through a pipe (148) to the biomass dryer (124) to supplement the heat used in the excess moisture removal process. Additionally, optionally, a fraction of the excess steam generated in the gasifier (128) is directed through a pipe (150) to a power generator (152) to produce electricity (154) to supplement the electricity from the electrolyzer (114). A fraction of the residual steam resulting from power generation passes through the heat exchanger (156) to obtain waste heat, which is directed through a pipe (160) to the biomass dryer (124) to supplement the heat used in the excess moisture removal process. The recovered water is then directed through a pipe (168) to the water electrolyzer (114). In addition, refinery gases (164 and 166), generated during the FischerTropsch reaction and the fractionation of the product, respectively, are used to ignite a duct burner (158) of the biomass dryer (124) to remove excess moisture from the biomass feedstock. Optionally, a fraction of the waste heat from the electrolysis stage is captured through Organic Rankine Cycle (ORC) technology and / or Sterling cycle generator (170) to produce electricity (154) to supplement the electricity from the electrolyzer (114). Optionally, the refinery gas (164) generated by the Fischer-Tropsch reaction and / or the refinery gas (166) generated by the fractionation process is used in an internal combustion engine or a microturbine (172) to generate power for the electrolyzer. Waste heat from the internal combustion engine is captured using organic Rankine cycle technology and / or a Sterling cycle generator to produce additional electricity. Although the invention has been described with reference to some of its specific embodiments, persons skilled in the art will understand that various modifications can be made without departing from the spirit and scope of the invention. All such modifications, obvious to persons skilled in the art, should be included within the scope of the following claims.

Claims

1. A process for preparing synthetic hydrocarbons from partially dried biomass feedstock, characterized in that it comprises: a) electrolysis of water in an electrolyzer to produce oxygen, hydrogen, and heat; b) feeding the oxygen generated in step a) and the partially dried biomass feedstock to a gasifier, and gasifying the feedstock under partial oxidation reaction conditions to generate hydrogen-poor syngas with an H2:CO ratio of approximately 1:1 and heat; c) adding at least a fraction of the hydrogen generated in step a) to the hydrogen-poor syngas generated in step b) to formulate hydrogen-rich syngas with an H2:CO ratio of approximately 2:1; d) reacting the hydrogen-rich syngas in a Fischer-Tropsch reactor to produce the synthetic hydrocarbons, refinery gas, water, and heat; e) recycling at least a fraction of the water produced in step d) for use in step a); and.f) recycling at least a fraction of the refinery gas generated in stage d) in an electric generator to produce electricity to supplement the electricity from the electrolyzer.

2. The process according to claim 1, further characterized in that the process additionally comprises the removal of excess moisture from the biomass feed material to obtain partially dry biomass feed material.

3. The process according to claim 2, further characterized in that it additionally comprises the recycling of at least a fraction of the heat generated in step d) in the step of removing excess moisture from the biomass raw material.

4. The process according to claim 2 or 3, further characterized in that it additionally comprises the recycling of at least a fraction of the heat generated in step a) in the step of removing excess moisture from the biomass raw material.

5. The process in accordance with any of claims 2 to 4, further characterized in that it additionally comprises the recycling of at least a fraction of the excess heat generated in step b) for the removal of excess moisture from the biomass feedstock.

6. The process according to any of claims 1 to 5, further characterized in that the heat obtained in step b) is generated in the form of steam, and the process further comprises recycling at least a fraction of the steam in an electric generator to produce electricity to supplement the electricity from the electrolyzer.

7. The process according to any of claims 1 to 6, further characterized in that the heat obtained in step d) is generated in the form of steam, and the process further comprises feeding at least a fraction of the steam into an electric generator to produce electricity to supplement the electricity from the electrolyzer. cbnccn / 77n7 / q / uili 8. The process in accordance with any of claims 1 to 7, further characterized in that it additionally comprises recycling the refinery gas to remove excess moisture from the biomass feedstock.

9. The process according to any of claims 1 to 8, further characterized in that it additionally comprises the fractionation of the synthesized hydrocarbons, where secondary refinery gas is generated during the fractionation.

10. The process according to claim 9, further characterized in that it additionally comprises recycling at least a fraction of the secondary refinery gas in an electric generator to produce electricity to supplement the electricity from the electrolyzer.

11. The process according to claim 9 or 10, further characterized in that it additionally comprises the recycling of at least a fraction of the secondary refinery gas to remove excess moisture from the biomass feedstock.

12. The process in accordance with any of claims 1 to 11, further characterized in that it additionally includes subjecting the synthesized hydrocarbons to a hydroprocessing operation.

13. The process according to claim 12, further characterized in that the hydroprocessing operation is selected from the group consisting of hydrocracking, thermocracking, hydrotreating, isomerization and combinations thereof.

14. The process according to any of claims 1 to 13, further characterized in that the hydrogen-poor syngas is subjected to a carbon dioxide removal operation prior to the reaction in the Fischer-Tropsch reactor.

15. The process according to claim 14, further characterized in that the separated carbon dioxide and / or steam is fed to the gasifier as a shielding gas.

16. The process according to any of claims 1 to 15, further characterized in that the biomass feedstock comprises municipal waste, wood waste, forest waste material, wastewater biomass, sewage biomass, agricultural waste, agricultural by-products, industrial fibrous material, harvested fibrous material, or mixtures thereof.