WO2014204302A1

WO2014204302A1 - Process for converting a biomass feedstock into at least a liquid hydrocarbon product

Info

Publication number: WO2014204302A1
Application number: PCT/NL2014/050387
Authority: WO
Inventors: Gerrit Brem
Original assignee: Universiteit Twente
Priority date: 2013-06-18
Filing date: 2014-06-13
Publication date: 2014-12-24
Also published as: EP3010993A1

Abstract

The invention provides a process for converting a biomass feedstock into at least a liquid hydrocarbon product wherein a biomass feedstock is provided and converted into at least a liquid hydrocarbon product by means of pyrolysis in the presence of a deoxygenation catalyst not comprising a transition metal as catalytically active component, followed by a hydrodeoxygenation step over a hydrodeoxygenation catalyst, wherein the hydrogen needed in the hydrodeoxygenation step is obtained by means of sorption-enhanced water-gas shift conversion of pyrolysis gas produced in the process.

Description

PROCESS FOR CONVERTING A BIOMASS FEEDSTOCK INTO AT LEAST A LIQUID HYDROCARBON PRODUCT Field of the Invention

The present invention relates to a process for converting a biomass feedstock into at least a liquid hydrocarbon product.

Background of the invention

It is known to convert biomass such as for example forestry and agricultural waste streams into a liquid hydrocarbon product by means of pyrolysis. Conventional pyrolysis of biomass results, however, in a liquid product that is, compared to fossil oil, highly oxygenated, acidic and viscous. Such liquid product is not stable, has a low energy density and is typically immiscible with refinery hydrocarbon feedstocks. In order to improve the product quality, products of conventional pyrolysis may be upgraded by means of hydroconversion. Such hydroconversion, however, requires large quantities of hydrogen and high pressures.

Alternatively, pyrolysis may be carried out in the presence of molecular hydrogen. Typically, an external source of hydrogen and high pressures are needed in known hydropyrolysis processes, making such processes economically unattractive.

In US2010/0256428 is disclosed a self-sustaining hydropyrolysis process for the conversion of biomass to a liquid product wherein no external source of hydrogen is required. In the process of US2010/0256428, the biomass is in a first stage pyrolysed in the presence of molecular hydrogen and a deoxygenation catalyst to produce a partially deoxygenated hydropyrolysis liquid and char. After removing the char from the liquid, the partially deoxygenated hydropyrolysis liquid is hydroconverted in the presence of a hydroconversion catalyst, and in the presence of gas comprising carbon oxides and light hydrocarbons generated in first stage, to produce a substantially fully deoxygenated hydrocarbon liquid and a gaseous mixture comprising carbon oxides and light hydrocarbons. The gaseous mixture produced in the second stage is then steam reformed to produce hydrogen for the hydropyrolysis step.

Although carried out at a much lower pressure than conventional hydropyrolysis processes, the process of US2010/0256428 still requires an elevated pressure. WO 2011/060556 Al describes a process for converting a biomass feedstock into a hydrocarbon product. Said process comprises the steps of subjecting a biomass feedstock to fast pyrolysis or hydropyrolysis followed by catalytically converting the resulting pyrolysis gas in a hydroconversion step to a hydrocarbon product and carbon dioxide, in the presence of hydrogen and steam over a carbon dioxide sorbent, while simultaneously generating hydrogen by reaction with steam.

Summary of the Invention

A novel pyrolysis process for the production of a stable liquid hydrocarbon product, and optionally also a gaseous hydrocarbon product or synthesis gas, has been found that can be operated at ambient pressure and wherein no external source of hydrogen is needed. In the new process, biomass is first pyrolysed in the presence of hydrogen and a first deoxygenation catalyst not comprising a transition metal as catalytically active component. Under these conditions, pyrolysis involves catalytic cracking (deoxygenation) and any hydrogen present during the pyrolysis is inert. The first deoxygenation catalyst only needs to partially deoxygenate hydrocarbonaceous compounds formed in the pyrolysis reaction. The first deoxygenation catalyst may therefore be a relatively cheap catalyst without a hydrogenating metal, such as for example carbonate minerals or clays. After separation of solids, i.e. char and spent first deoxygenation catalyst, from the pyrolysis effluent, partially deoxygenated hydrocarbonaceous compounds formed in this first stage are further deoxygenated in the presence of a second deoxygenation catalyst in a second stage, wherein the second deoxygenation catalyst comprises a transition metal as catalytically active component. The second stage is a hydrodeoxygenation step using a hydrodeoxygenation catalyst.

In the second stage, a gaseous stream is obtained which is, after condensation, separated into a liquid product stream and pyrolysis gas. At least part of the pyrolysis gas is recycled to the first stage, i.e. the pyrolysis step.

Carbon monoxide formed in the pyrolysis step is subjected to water-gas shift conversion by contacting either the pyrolysis gas obtained after condensation or the gaseous pyrolysis effluent from which solids are separated, with a hot carbon dioxide sorbent to capture carbon dioxide in the presence of water vapour. The hydrogen-rich stream thus obtained, i.e. sorption-enhanced water-gas shifted pyrolysis gas or sorption- enhanced water-gas shifted pyrolysis effluent, is supplied to the hydrodeoxygenation step or recycled to the pyrolysis step, respectively.

Char and spent first deoxygenation catalyst from the first stage are supplied to a regenerator wherein char is used as fuel and spent first deoxygenation catalyst is regenerated. Spent carbon dioxide sorbent is also regenerated in a regenerator. In a preferred embodiment, the two regeneration steps are combined and spent sorbent carried by the sorption-enhanced, water-gas shifted pyrolysis gas is supplied to the pyrolysis step and a stream of solids comprising char, spent first deoxygenation catalyst and spent sorbent obtained in this step is supplied to a common regenerator.

Accordingly, the present invention provides a process for converting a biomass feedstock into at least a liquid hydrocarbon product, the process comprising the following steps:

a) providing a biomass feedstock;

b) subjecting the biomass feedstock in a pyrolysis reactor in the presence of a first deoxygenation catalyst and hydrogen to pyrolysis to obtain a first gaseous stream comprising partially deoxygenated hydrocarbonaceous compounds, carbon oxides and hydrogen, and a stream of solids comprising char and spent first deoxygenation catalyst, wherein the first deoxygenation catalyst is a catalyst that does not comprise a transition metal as catalytically active component;

c) supplying the stream of solids to a regenerator to regenerate the spent first deoxygenation catalyst to obtain regenerated first deoxygenation catalyst;

d) recycling the regenerated first deoxygenation catalyst to pyrolysis step b);

e) subjecting the partially deoxygenated hydrocarbonaceous compounds to further deoxygenation by contacting the first gaseous stream with a second deoxygenation catalyst under deoxygenation conditions to obtain a second gaseous stream comprising hydrocarbons, wherein the second deoxygenation catalyst comprises a transition metal as catalytically active component, wherein the further deoxygenation is hydrodeoxygenation and wherein the second deoxygenation catalyst is a hydrodeoxygenation catalyst;

f) condensing the second gaseous stream to obtain pyrolysis gas comprising CI to C3 hydrocarbons and pyrolysis oil and recovering pyrolysis oil as liquid hydrocarbon product; g) recycling at least part of the pyrolysis gas to the pyrolysis reactor;

h) subjecting carbon monoxide formed during step b) to water-gas shift conversion, in the presence of a hot carbon dioxide sorbent and water vapour, by contacting at least part of the pyrolysis gas obtained in step f) prior to recycling such gas to step b, or the first gaseous stream obtained in step b) prior to step e), with hot carbon dioxide sorbent to obtain a water-gas shifted gaseous stream and spent sorbent; and

i) supplying the spent sorbent to a regenerator to regenerate the sorbent and to obtain hot regenerated carbon dioxide sorbent,

wherein the contacting in step h) comprises mixing the hot regenerated carbon dioxide sorbent with at least part of the pyrolysis gas obtained in step f) or with the first gaseous stream obtained in step b).

An important advantage of the process of the invention is that the entire process can be carried out at ambient pressure. Moreover, no hydrogen is needed from an external source. All hydrogen needed in hydrodeoxygenation step e) can be provided by hydrogen produced by water-gas shifting the carbon monoxide formed during pyrolysis. Moreover, the heat needed in the process may be provided by the combustion of char produced in the pyrolysis step in regeneration step c). Summary of the Drawings

In Figure 1 is schematically shown a process according to the invention wherein regeneration steps c) and i) are combined.

In Figure 2 is schematically shown a process according to the invention with separate regeneration steps c) and i).

In Figure 3 is schematically shown a process according to the invention wherein the sorption-enhanced water-gas shift conversion zone is placed after the pyrolysis reactor.

Detailed Description of the Invention

In the process according to the invention, a biomass feedstock is provided and converted into at least a liquid hydrocarbon product by means of pyrolysis in the presence of a first deoxygenation catalyst and hydrogen, followed by a further deoxygenation step. The biomass feedstock may be any suitable carbonaceous biomass feedstock such as for example a lignocellulosic biomass such as wood, straw, bagasse, miscanthus, grasses, reed, bamboo, rice husks, agricultural waste streams or paper sludge or other types of biomass such as for example manure, digestate, or sewage sludge. Preferably, the biomass feedstock comprises comminuted biomass, i.e. fibres or small particles, that can be transported by a carrier gas stream.

In pyrolysis step b), the biomass feedstock is subjected to pyro lysis in a pyrolysis reactor in the presence of a first deoxygenation catalyst and hydrogen. This is suitably done by supplying a biomass feedstock and a hydrogen-rich carrier gas comprising first deoxygenation catalyst to the pyrolysis reactor. The hydrogen-rich carrier gas is gas produced in pyrolysis step b) that has been water-gas shifted in the presence of a carbon dioxide sorbent in step h) of the process. The water-gas shifted gas that is used as carrier gas for the biomass feedstock and the first deoxygenation catalyst may comprise spent carbon dioxide sorbent particles. If that is the case, spent carbon dioxide sorbent is supplied with the carrier gas to the pyrolysis reactor.

In pyrolysis step b), only partial deoxygenation is needed. The first deoxygenation catalyst is a catalyst that does not comprise a transition metal as catalytically active component. Preferably, the first deoxygenation catalyst comprises a carbonate, a clay, a metal oxide or a combination of one or more thereof. Examples of suitable first deoxygenation catalysts are catalysts comprising cationic or anionic clay, natural clay, hydrotalcite, bauxite, carbonates of alkali or alkaline earth metals. More preferably, the catalyst comprises sodium carbonate, magnesium carbonate, or a combination thereof. Preferably, the first deoxygenation catalyst is a catalyst that also has water-gas shift activity. An example of a first deoxygenation catalyst with water- gas shift activity is sodium carbonate.

The first deoxygenation catalyst is a solid catalyst, preferably a solid catalyst having a particle size in the range of from 0.1 to 3 mm, more preferably in the range of from 0.2 to 2 mm, even more preferably of from 0.3 to 1 mm.

Pyrolysis step b) may be carried out in any suitable pyrolysis reactor. Suitable reactors are known in the art and comprise fluidised bed reactors, downers, risers, moving bed reactors, transported bed reactors, rotating cone reactors and cyclone reactors. Preferably, pyrolysis is carried out in a reactor suitable for pyrolysing biomass feedstock entrained or fluidised in a stream of carrier gas. An example of a suitable reactor is the pyrolysis reactor disclosed in WOO 1/34725.

Pyrolysis step b) may be carried out under any suitable pyrolysis conditions. Preferably, the pyrolysis conditions comprise a temperature in the range of from 350 to 650 °C, more preferably of from 400 to 550 °C. It is an advantage of the process according to the invention that no elevated pressure is needed in pyrolysis step b). Since no full deoxygenation of oxygenated hydrocarbonaceous compounds formed by pyrolysis is needed during step b), step b) may be carried out at ambient pressure or a pressure close to ambient pressure. Preferably, step b) is carried out at a pressure in the range of from 0.5 to 11 bar (absolute), more preferably of from 1 to 10 bar (absolute), even more preferably of from 1 to 5 bar (absolute), still more preferably of from 1 to 1.5 bar (absolute), most preferably at or close to ambient pressure.

In pyrolysis step b) is obtained a first gaseous stream comprising gaseous compounds formed in the pyrolysis of biomass and a stream of solids comprising char and spent catalyst. A solid-gas separation may take place inside the pyrolysis reactor, in which case the first gaseous stream and the stream of solids are discharged from the pyrolysis reactor as separate streams. Alternatively, a stream comprising both gaseous compounds and solids is discharged from the pyrolysis reactor and gas-solids separation into the first gaseous stream and the stream of solids takes place outside the pyrolysis reactor.

The first gaseous stream comprises partially deoxygenated hydrocarbonaceous compounds, carbon oxides including carbon monoxide, and hydrogen, and typically further comprises hydrocarbons.

The stream of solids comprises char formed by pyrolysing the biomass and first deoxygenation catalyst particles on which coke is deposited (spent catalyst). The stream of solids is in step c) supplied to a regenerator to regenerate the spent catalyst by burning carbon deposits from the catalyst to obtain regenerated first deoxygenation catalyst. Regeneration of catalysts on which carbon is deposited is well-known in the art and any suitable regenerator and regeneration conditions may be used. Typically, an oxidant, preferably air, is supplied to the regenerator and the char present in the stream of solids serves as fuel for the combustion reaction. Coke deposited on the spent catalyst are burnt off and hot regenerated first deoxygenation catalyst is obtained. Typical regeneration conditions comprise a temperature in the range of from 600 to 1, 150 °C, more preferably in the range of from 700 to 1, 100 °C, even more preferably in the range of from 750 to 900 °C. The regenerated first deoxygenation catalyst is recycled to pyrolysis step b), either directly or indirectly via sorption-enhanced water- gas shift conversion step h). Step h) will be described in more detail hereinbelow.

In step e), the first gaseous stream comprising partially deoxygenated hydrocarbonaceous compounds obtained in pyrolysis step b) is supplied to a reaction zone for further deoxygenation of the partially deoxygenated hydrocarbonaceous compounds by contacting the first gaseous stream with a second deoxygenation catalyst comprising a transition metal as catalytically active component under deoxygenation conditions, wherein the further deoxygenation is hydrodeoxygenation and wherein the second deoxygenation catalyst is a hydrodeoxygenation catalyst. Preferably, the hydrodeoxygenation catalyst comprises a transition metal of any one of groups 6 to 10 of the periodic table of elements.

The hydrogen needed in hydrodeoxygenation step e) is obtained by means of sorption-enhanced water-gas shift conversion of carbon monoxide produced in the process.

Optionally, any remaining solid compounds are removed from the first gaseous stream prior to supplying this stream to step e). Such solids removal may be done by any suitable means known in the art, for example by means of a cyclone. In one embodiment, the first gaseous stream is first subjected to sorption-enhanced water-gas shift conversion step h) before being subjected to hydrodeoxygenation step e).

Hydrodeoxygenation catalysts are known in the art and any suitable hydrodeoxygenation catalyst, comprising a transition metal as catalytically active component, known in the art may be used. Preferably, the hydrodeoxygenation catalyst comprises cobalt or nickel or a combination of cobalt or nickel with molybdenum or tungsten or comprises one or more noble metals. The hydrodeoxygenation catalyst may for example be a catalyst comprising NiMo, CoMo, CoW, or NiW, preferably in sulphided form, or a catalyst comprising a metal selected from Pd, Pt, Rh, Ni, Ru and combinations of two or more thereof. More preferably, the hydrodeoxygenation catalyst comprising a metal selected from Pd, Pt, Rh, Ni, Ru and combinations of two or more thereof.

In step e), the deoxygenation conditions may comprise any suitable hydrodeoxygenation conditions known in the art. Preferably such conditions comprise a temperature in the range of from 260 to 550 °C, more preferably of from 270 to 500 °C, even more preferably of from 280 to 450 °C, still more preferably of from 300 to 400 °C.

Step e) is carried out in a reaction zone that is such that the catalyst is retained in the reaction zone. Any catalyst arrangement may be used, such as for example a fixed bed of catalyst particles or a monolithic, metallic or carbon structure supporting catalytically active components, a fluidised bed, a moving bed or an entrained flow reactor.

Step e) is preferably carried out at the same pressure as step b), more preferably at a pressure in the range of from 1 to 10 bar (absolute), even more preferably of from 1 to 5 bar (absolute), still more preferably of from 1 to 1.5 bar (absolute), still more preferably at or close to ambient pressure.

In step e) is obtained a second gaseous stream comprising hydrocarbons. The second gaseous stream may further obtain carbon oxides and/or hydrogen. The second gaseous stream may still comprise oxygenated hydrocarbonaceous compounds, preferably less than 30 wt%, more preferably less than 20 wt%, even more preferably less than 15 wt%, still more preferably less than 10 wt%. The second gaseous stream is condensed in step f) to obtain pyrolysis gas and pyrolysis oil. Condensation of a gaseous stream obtained in pyrolysis is well-known in the art. Any known condenser and condensing conditions may be used in step f).

Pyrolysis oil is recovered from the process as liquid hydrocarbon product. The pyrolysis oil thus obtained comprises mainly hydrocarbons and no or only a low amount of oxygenated hydrocarbonaceous compounds. Therefore, the pyrolysis oil is stable and has a high energy density.

In condensation step f) is further obtained pyrolysis gas. The pyrolysis gas comprises CI to C3 hydrocarbons and may further comprise carbon oxides and hydrogen. The second gaseous stream obtained in hydrodeoxygenation step e) will typically also comprises some H₂0. In case condensation step f) is carried out at a temperature at which not all H₂0 in the second gaseous stream is condensed, the stream of pyrolysis gas will also comprise some water vapour.

In step g), at least part of the pyrolysis gas obtained in condensation step f) is recycled to pyrolysis step b). A small part of the pyrolysis gas will typically be purged from the process in order to avoid a too large pyrolysis gas recycle. The purged gas may for example be used for local heat or electricity production. Part of the pyrolysis gas may be recovered as product stream, optionally after a further treatment step, for example in case methane or synthesis gas is the desired product.

The process further comprises a step h) wherein carbon monoxide formed during step b) is subjected to water-gas shift conversion in the presence of a hot carbon dioxide sorbent. This is done by contacting either at least part of the pyrolysis gas obtained in step f) or the first gaseous stream obtained in step b) with hot carbon dioxide sorbent in the presence of water vapour and preferably in the presence of a water-gas shift catalyst. If pyrolysis gas obtained in step f) is subjected to sorption- enhanced water-gas shift conversion step h), this is done before such pyrolysis gas is recycled to pyrolysis step b). If the first gaseous stream obtained in step b) is subjected to step h), this is done prior to supplying the first gaseous stream to hydrodeoxygenation step e). In step h) the gaseous stream, i.e. pyrolysis gas or the first gaseous stream, is contacted with the sorbent by mixing hot regenerated sorbent obtained in sorbent regeneration step i) with the gaseous stream. In step h), a water-gas shifted gaseous stream and spent sorbent is obtained.

Any suitable carbon dioxide sorbent may be used in step h), for example calcium oxide, magnesium oxide, calcium hydroxide, hydrotalcite, lithium zirconate, lithium orthosilicate or other metal oxides or hydroxides that can react with carbon dioxide to form a carbonate phase. Preferably, the carbon dioxide sorbent comprises calcium oxide, for example in the form of calcined limestone or dolomite or supported on a suitable carrier such as alumina.

In step h) the gaseous stream, i.e. pyrolysis gas or first gaseous stream, is contacted with hot carbon dioxide sorbent in the presence of water vapour and preferably in the presence of a water-gas shift catalyst. Under these conditions, water- gas shift conversion takes place, i.e. carbon monoxide in the pyrolysis gas or first gaseous stream reacts with water to form carbon dioxide and hydrogen. Carbon dioxide formed reacts with the carbon dioxide sorbent to form spent sorbent. The spent sorbent formed in step h) is typically a carbonate. Since carbon dioxide is withdrawn, the reaction equilibrium is drawn towards the formation of hydrogen and a hydrogen-rich gas (water-gas shifted gaseous stream) is obtained.

The spent sorbent obtained in step h) is supplied to a regenerator to regenerate the sorbent and to obtain hot regenerated sorbent (regeneration step i)). Step h) is carried out by mixing the hot regenerated sorbent with at least part of the pyrolysis gas obtained in step f) or with the first gaseous stream obtained in step b). Such mixing may be done in any suitable way, for example by injecting the hot regenerated sorbent in the gaseous stream to be subjected to water-gas shift conversion. By mixing the hot regenerated carbon dioxide sorbent in the gaseous stream, the gaseous stream is brought to an elevated temperature, typically in the range of from 450 to 750 °C, preferably of from 550 to 700 °C, more preferably of from 600 to 700 °C.

The contacting of the pyrolysis gas or first gaseous stream with carbon dioxide sorbent in step h) is carried out in the presence of water vapour. In case pyrolysis gas obtained in condensation step f) is converted and the condensation is carried out at a relatively high temperature, for example in the range of from 30 to 60 °C, the pyrolysis gas may comprise sufficient water vapour for the water-gas shift reaction to occur in step h). Preferably, an external source of water is added to the pyrolysis gas or the first gaseous stream prior to, simultaneously with or just after mixing the hot regenerated sorbent with the gaseous stream. Alternatively or additionally, biomass feedstock containing some moisture may be added to the pyrolysis gas prior to, simultaneously with or just after mixing the hot regenerated sorbent with the pyrolysis gas in order to provide water vapour for the water-gas shift reaction.

Step h) is preferably carried out in the presence of a water-gas shift catalyst. Such catalysts are known in the art. Any suitable water-gas shift catalyst known in the art may be used, for example iron-chrome oxides, copper-zinc-alumina, magnesium oxide or other oxides of transition metals, alkali salts, or alkali promoted alumina.

In the process according to the invention, separate solid materials may be used as water gas shift conversion catalyst, first deoxygenation catalyst and carbon dioxide sorbent. Alternatively, two or three of these functions, i.e. water-gas shift conversion catalytic activity, first deoxygenation catalytic activity and carbon dioxide sorption, may be combined in a single solid material. This may for example be done by supporting two or three of these functions on a single solid support material, for example a water-gas shift catalytic material and carbon dioxide sorptive material on an alumina carrier. Alternatively, a solid compound or material may be used that has two or three of these functions. Sodium carbonate for example may act both as first deoxygenation catalyst and as water-gas shift catalyst. Another example is dolomite that comprises both calcium oxide that acts as carbon dioxide sorbent and magnesium oxide that acts as a water-gas shift catalyst.

In the case the first deoxygenation catalyst is present during step h) and the first deoxygenation catalyst has water-gas shift catalytic activity, there is no need to use a dedicated water-gas shift catalyst in the process. Examples of first deoxygenation catalysts having water-gas shift catalytic activity are sodium carbonate and hydrotalcite. Also in case the carbon dioxide sorbent has water-gas shift catalytic activity, e.g. dolomite, there no need to use a dedicated water-gas shift catalyst in the process.

In step h) is obtained spent sorbent carried by the water-gas shifted gaseous stream. The spent sorbent may be separated from the water-gas shifted gaseous stream prior to supplying such stream to pyrolysis step b) or to hydrodeoxygenation step e). If that is the case, a separate regenerator for regenerating sorbent in step i) is needed.

In case pyrolysis gas obtained in step f) is subjected to sorpti on-enhanced water- gas shift conversion in step h), the water-gas shifted pyrolysis gas is preferably supplied to pyrolysis step b) with the spent sorbent, and the stream of solids comprising char, spent first deoxygenation catalyst and spent sorbent obtained in step b) is supplied to a common regenerator wherein both the spent catalyst and the spent sorbent are regenerated. In the common regenerator a mixture comprising hot regenerated first deoxygenation catalyst and hot regenerated sorbent is obtained. In fact, regeneration steps c) and i) are combined in this embodiment. In step h), the mixture comprising hot regenerated first deoxygenation catalyst and hot regenerated sorbent is mixed with at least part of the pyrolysis gas obtained in step f). An advantage of using a common regeneration step, wherein a mixture of regenerated first deoxygenation catalyst and regenerated sorbent is obtained that is subsequently mixed with the pyrolysis gas obtained in step f), is that first deoxygenation catalyst is present during step h) and may catalyse the water-gas shift reaction. Preferably therefore, the first deoxygenation catalyst is a catalyst with water-gas shift activity such as for example sodium carbonate. A further advantage is that only one regenerator, i.e. the common regenerator, is needed in the process. Moreover, char produced in pyrolysis step b) is used as fuel for the regenerator in step c) and, if steps c) and i) are combined, for the common regenerator, whereas in case of two separate regenerators, an external source of fuel would be needed for the separate sorbent regenerator in step i). In case regeneration steps c) and i) are combined, a support carrying a first deoxygenation catalyst and a water-gas shift catalyst (or a catalyst having both catalytic functions) and a carbon dioxide sorbent may be used.

The regenerator in step i) and, if steps c) and i) are combined, the common regenerator may be operated at any suitable temperature, preferably at a temperature in the range of from 750 to 900 °C.

Preferably, the entire process is carried out at a pressure in the range of from 1 to 10 bar (absolute), more preferably of from 1 to 5 bar (absolute), even more preferably of from 1 to 1.5 bar (absolute). It is particularly preferred to carry out the entire process at ambient pressure.

Detailed Description of the Drawings

The process according to the invention will be further illustrated by means of the following, non-limiting drawings.

In Figure 1 is shown a process diagram of a process according to the invention wherein regeneration steps c) and i) are combined. Biomass feedstock is added via line 1 to a stream comprising spent sorbent and regenerated sodium carbonate particles (regenerated first deoxygenation catalyst) entrained in a hydrogen-rich gaseous stream in line 3. Thus, a stream comprising biomass, spent sorbent and sodium carbonate particles carried by a hydrogen-rich gaseous stream is formed that is supplied via line 4 to pyrolysis reactor 5. In pyrolysis reactor 5, the biomass feedstock is subjected to pyrolysis, preferably at a temperature in the range of from 400 to 600 °C, to form char, oxygenated hydrocarbonaceous compounds, hydrocarbons, carbon oxides and hydrogen. The oxygenated hydrocarbonaceous compounds are partially deoxygenated, catalysed by the sodium carbonate. A stream of solids comprising char, coked sodium carbonate particles and spent sorbent is withdrawn via line 6 from reactor 5 and supplied to common regenerator 7. First gaseous stream is withdrawn via line 8 from reactor 5 and, optionally after removal of remaining solids such as char dust and fine catalyst and sorbent particles (not shown), supplied to hydrodeoxygenation reaction zone 9. In zone 9 is contained a fixed bed of hydrodeoxygenation catalyst particles comprising a transition metal as catalytically active component, for example Pt supported on alumina. In zone 9, the partially deoxygenated hydrocarbonaceous compounds in the first gaseous stream are further deoxygenated, preferably at a temperature in the range of from 380 to 500 °C, and the resulting second gaseous stream is supplied via line 10 to condensing zone 11 and condensed to obtain liquid pyrolysis oil 12 and pyrolysis gas 13. Liquid pyrolysis oil is recovered from the process as product. Part of pyrolysis gas 13 is purged via line 14 and part is recycled to pyrolysis reactor 5 via line 15.

In common regenerator 7, spent catalyst (coked sodium carbonate particles) is regenerated by burning off the carbon deposits. At the high temperature prevailing in regenerator 7, typically in the range of from 750 to 1,000 °C, calcium carbonate (spent sorbent) is thermally decomposed to form calcium oxide (regenerated sorbent) and carbon dioxide. Air is supplied via line 16 to regenerator 7 as oxidant and char in the stream of solids supplied via line 6 serves as fuel. Flue gas is withdrawn from regenerator 7 via line 17. In regenerator 7, a mixture 18 of hot regenerated carbon dioxide sorbent (calcium oxide) and hot regenerated first deoxygenation catalyst (sodium carbonate on alumina) is formed. The hot mixture is injected in the pyrolysis gas that is recycled via line 15 to pyrolysis reactor 5. Water vapour is added via line 19 to the recycled pyrolysis gas. Thus, the pyrolysis gas is brought in contact with hot regenerated carbon dioxide sorbent in the presence of water vapour in zone 20 under conditions at which water-gas shift reaction takes place. The regenerated first deoxygenation catalyst has water-gas shift activity and serves as the water-gas shift catalyst. The temperature in zone 20 is typically in the range of from 600 to 700 °C. In zone 20, a stream comprising spent sorbent and regenerated sodium carbonate particles entrained in a hydrogen-rich gaseous stream is formed, which is, after adding biomass particles and optionally make up sodium carbonate particles, supplied via line 4 to pyrolysis reactor 5.

Alternatively, part of or the entire biomass feedstock may be added via line 21 to the process just upstream of zone 20, to provide water for the water vapour needed in zone 20. In this embodiment, addition of water vapour via line 19 is not needed.

In order to make up for any losses of first deoxygenation catalyst or sorbent, for example with the flue gas withdrawn from the process via line 17, make-up catalyst and/or sorbent may be added to the process, for example to regenerator 7 via line 22.

In Figure 2 is shown a process diagram of a process according to the invention with separate regeneration steps c) and i). Corresponding reference numbers have the same meaning as in Figure 1. In the process of Figure 2, pyrolysis gas is supplied via line 15 to zone 20 and hot regenerated carbon dioxide sorbent and water-gas- shift catalyst are supplied via line 23 to zone 20. A hydrogen-rich gaseous stream comprising spent sorbent (calcium carbonate) and water-gas shift catalyst is formed in zone 20. This stream is supplied via line 30 to gas-solids separator 31 wherein it is separated into a stream of solids comprising spent sorbent and water-gas shift catalyst and a hydrogen-rich gaseous stream. The hydrogen-rich gaseous stream is recycled to pyrolysis reactor 5 via line 33. The stream of solids is supplied via line 35 to sorbent regenerator 36 to which oxidant and fuel is supplied via lines 37 and 38, respectively. In regenerator 36, spent sorbent is regenerated and the water-gas shift catalyst is heated and hot regenerated sorbent and water-gas shift catalyst are brought in contact with the pyrolysis gas recycled via line 15 in order to water-gas shift the pyrolysis gas in zone 20. Flue gas is withdrawn from regenerator 36 via line 39. Make-up sorbent and water-gas shift catalyst may be added to regenerator 36 (not shown).

The stream of solids that is withdrawn from pyrolysis reactor 5 via line 6 comprises char and spent first oxidation catalyst (coked sodium carbonate particles) and no or only a very small amount of spent sorbent. This stream is supplied to catalyst regenerator 40 to which oxidant is supplied via line 41. Spent catalyst is regenerated to form regenerated first oxidation catalyst that is recycled via line 42 to pyrolysis reactor 5. Flue gas is withdrawn from regenerator 40 via line 43.

In Figure 3 is shown a process diagram of a process according to the invention wherein sorption-enhanced water-gas shift conversion zone 20 is placed after pyrolysis reactor 5. Corresponding reference numbers have the same meaning as in Figures 1 and 2.

In the process of Figure 3, first gaseous stream obtained in pyrolysis reactor is supplied via line 8 to sorption-enhanced water-gas shift conversion zone 20. A mixture of hot regenerated carbon dioxide sorbent and water-gas-shift catalyst are supplied via line 23 to zone 20. A hydrogen-rich gaseous stream comprising spent sorbent (calcium carbonate) and water-gas shift catalyst is formed in zone 20. This stream is supplied via line 30 to gas-solids separator 31 wherein it is separated into a stream of solids comprising spent sorbent and water-gas shift catalyst and a hydrogen-rich gaseous stream comprising partially deoxygenated hydrocarbons. The hydrogen-rich gaseous stream is supplied to hydrodeoxygenation reaction zone 9 via line 33.

Claims

1. A process for converting a biomass feedstock into at least a liquid hydrocarbon product, the process comprising the following steps:

a) providing a biomass feedstock;

d) recycling the regenerated first deoxygenation catalyst to pyrolysis step b);

f) condensing the second gaseous stream to obtain pyrolysis gas comprising CI to C3 hydrocarbons and pyrolysis oil and recovering pyrolysis oil as liquid hydrocarbon product;

g) recycling at least part of the pyrolysis gas to the pyrolysis reactor;

h) subjecting carbon monoxide formed during step b) to water-gas shift conversion, in the presence of a hot carbon dioxide sorbent and water vapour, by contacting at least part of the pyrolysis gas obtained in step f) prior to recycling such gas to step b), or the first gaseous stream obtained in step b) prior to step e), with hot carbon dioxide sorbent to obtain a water-gas shifted gaseous stream and spent sorbent; and

A process according to claim 1 wherein in step h) carbon monoxide formed during step b) is subjected to water-gas shift conversion in the presence of a water-gas shift catalyst.

A process according to claim 1 or 2, wherein regeneration steps c) and i) are combined, wherein:

spent sorbent is supplied to the pyrolysis reactor with the pyrolysis gas that is recycled to the pyrolysis reactor;

the stream of solids obtained in pyrolysis step b) comprises char, spent first deoxygenation catalyst and spent sorbent;

steps c) and i) are carried out by supplying the stream of solids to a common regenerator to obtain a mixture of hot regenerated first deoxygenation catalyst and hot regenerated carbon dioxide sorbent; and in step h) the mixture of hot regenerated first deoxygenation catalyst and hot regenerated carbon dioxide sorbent is mixed with at least part of the pyrolysis gas obtained in step f).

A process according to any one of the preceding claims, wherein the first deoxygenation catalyst comprises sodium carbonate, magnesium carbonate or a combination thereof.

A process according to any one of the preceding claims, wherein two or three materials selected from the first deoxygenation catalyst, the water-gas shift catalyst and the carbon dioxide sorbent, are supported on a common carrier material. A process according to any one of the preceding claims, wherein the carbon dioxide sorbent comprises calcium oxide.

A process according to any one of the preceding claims, wherein no hydrogen from an external source is added to the process.

A process according to any one of the preceding claims, wherein the process is carried out at a pressure in the range of from 1 to 5 bar (absolute).

A process according to any one of the preceding claims, wherein the hydrodeoxygenation catalyst in step e) comprises a metal selected from Pd, Pt, Rh, Ni, Ru and combinations of two or more thereof.

A process according to any one of the claims 1-9, wherein step e) is carried out at a temperature in the range of from 270 to 500 °C.

A process according to any one of the preceding claims, wherein step b) is carried out at a temperature in the range of from 350 to 650 °C.

A process according to any one of the preceding claims, wherein step h) is carried out at a temperature in the range of from 450 to 750 °C.