In previous comments dated 03/11/2022 and 28/10/2022, we presented our thoughts regarding the current status of Small-scale GTL technologies, as well as the results of a statistical analysis of patenting activity in the field of syngas production by Small-scale GTL. In this note, we will try to analyze the main trends in recent patent solutions.
One of the most popular trends in patent solutions related to the production of syngas by Small-scale GTL addressing the High OPEX / Repair and replacement problem. It includes patents and patent applications that propose technical solutions aimed at increasing the service life of reactors, improving the corrosion resistance of the materials involved, eliminating the problems of uncontrolled deactivation of catalysts, and others. Another trend emerges from a large group of patent documents that address the use of microchannel technologies for the production of products other than syngas, or the universal use of Small-scale GTL. The third direction is based on the traditional objectives of GTL technologies related to the production of hydrocarbons through the Fischer-Tropsch synthesis. Below are some examples of patent solutions related to the mentioned trends.
High OPEX / Repair and replacement
Patent application WO2017215789A1 by L'air Liquide (FR) proposes a reactor for steam reforming of hydrocarbon-containing gas for syngas production. The reactor shell contains a reforming zone and a water gas shift reaction zone. The reactor has a tubular form and is equipped with burners to indirectly provide heat to the reforming reaction. The reactor also contains at least one steam reforming tube, which consists of an outer reforming tube with feed gas supply openings and syngas outlet openings on one side and closed on the other side. The interior of the outer tube is partially dedicated to the steam reforming reaction zone in which the catalyst is loaded. The interior of the closed side of the outer tube includes a cavity separated from the catalytic layer by a gas-permeable separator. Inside the outer tube, an inner screw-shaped tube for water gas shift conversion is also positioned, the inner wall of this tube contains the corresponding catalyst in the form of molded elements, such as granules, honeycombs, etc. This catalyst can comprise Al, Ce, Zr, Fe, Cr, Zn, and/or Cu as metal or oxide, particularly CeZrOx is proposed by the authors.
The heat supply, steam reforming, and water gas shift conversion zone structures contain microchannels arranged in parallel to each other in such a way that heat exchange between them is possible through the walls of the channels. The channels are positioned in a unit, produced by 3D printing. With regard to the invention, the authors mention a reduction in the risks of destruction of the reactor materials due to corrosion caused by metal dusting.
The document was published in 2017 and has another related application published in CNIPA (CN) in 2019.
Image from: WO2017215789A1
Patent US9381488B2 published by Korea Institute of Science and Technology (KIST) (KR) discloses a micro-reactor for hydrocarbon reforming, in which both endothermic and exothermic reactions take place simultaneously. The microreactor includes an end plate, and one or more modules, each of which contains: a combustion channel plate, a platinum combustion catalyst plate, a reforming channel plate, a Nickel reforming catalyst plate. The combustion catalyst plate has parts loaded with catalyst and parts without catalyst. The parts filled and unfilled with the combustion catalyst are placed alternatingly in a lattice form, from the reagent inlet to the product outlet.
The authors claim that the invention set forth in the patent can solve the problem of local temperature increase, thus reducing temperature differences that lead to a decrease in the strength of the materials used and to thermal deactivation of the catalyst.
The patent family consists of 4 documents published in the US and KR between 2014 and 2016.
Image from: US9381488B2
Patent CN106582467B published by SINOPEC Engineering Incorporation (CN) proposes a dual radial direction microchannel reactor in which one exothermic and one endothermic reaction, such as catalytic combustion and steam methane reforming, are performed simultaneously. The reactor contains a cylindrical sealed and pressure-bearing body, and two straight tubes, the first of which is placed on the top part of the body, while the second one – on the bottom part. A radial catalysis module positioned between the two straight tubes, it has the form of a central cylinder and is equipped with 1-100 sleeves placed outside the central cylinder. The central cylinder and sleeves are equipped with microchannels, the inner and outer walls of which are loaded with catalysts for different reactions, respectively. Each microchannel has an outer and inner hole, and its diameter is from 2 to 50mm and gradually decreases from the outer to the inner hole. One part of the sleeve is separated by a baffle that separates the collection channel and the bypass channel. The second part of the sleeve is separated from the outer part of the body by a gap. The inner holes of the microchannels of each sleeve and the central cylinder are in fluid communication with the second straight tube through the collection channel. The sleeves also include chambers formed by the inner walls of the sleeve and the outer walls of the microchannels, while the upper part of the chamber of the sleeve communicates with the hole in the upper part of the body, and the lower part of the chamber of the sleeve communicates with the hole in the lower part of the body. The feedstock supplied through the first straight tube reacts inside the microchannels and the reaction products are discharged through the second straight tube. The feedstock for the second reaction is supplied into the hole in the upper part of the body, it undergoes the second catalytic reaction on the outer walls of the microchannels, where the second catalyst is located; the product of this reaction is discharged through the second outlet in the upper part of the body.
The inventors also indicate that the reduced residence time of the gases in the reactor increases the service life of the catalysts by 15-20%, and also reduces the cost of manufacturing the reactor and increases its efficiency.
The application/patent pair was published by the Chinese Patent Office in 2017 and 2018.
Image from: CN106582467B
Universal use of Small-scale GTL
Document US10106406B2 published by Watt Fuel Cell Corp (US) proposes a chemical reactor consisting of a plurality of tubular reactor modules and containing an inlet channel and a manifold connected to it. The collector housing includes a chamber; a gaseous reactants distributor connected to the gas pipeline, occupying a large part of the chamber and containing outlet openings located in the opposite direction from the inlet channel; a heater thermally connected to the collector chamber and made in the form of a resistive electric heater or a heat-conducting element connected to the reaction zone. The inlet channel and the manifold body are connected by a gas-tight seal. According to the text of the document, the chemical reactor can be made in a microchannel form and used for a variety of reactions, including reforming, gasification, FT synthesis, partial oxidation, etc. The authors suggest the use of the invention in a fuel cell system and point out the need to create compact, reliable and efficient devices.
The patent family contains 50 documents, 18 of which are related to the subject of synthesis gas production. Patent documents on the subject of interest were published in CA CN AU US JP EP MX WO from 2015 to 2021.
Image from US10106406B2
SINOPEC Engineering Incorporation (CN) Patent CN106582468B describes an axial microchannel reactor having a cylindrical sealed pressure-resistant casing, a first straight tube extending from the top of the casing to the interior of the casing, a second straight tube extending from the bottom of the casing to the interior of the casing, and a catalytic reaction unit located in the casing between the first and second straight tubes.
The catalytic reaction unit contains hollow cylinders coaxial with the body and connected to it by the outer side; the adjacent cylinders are separated by a gap. Each of the cylinders includes axial microchannels. The second straight tube is in fluid communication with the axial microchannels in each of the cylinders. A plurality of paired openings is positioned on different lateral sides of the unit, the openings are in fluid communication with each other through the cylinder chambers. The inner and outer surfaces of the microchannels are loaded with catalytically active elements. The microchannels have a diameter of 2mm-50mm, it gradually decreases from the top to the bottom so that the ratio of the diameters is (2-20):1. The total volume of the internal space of the microchannels is 30%-80% of the catalytic reaction unit.
The feed of the first catalytic reaction is supplied into the reactor through the first straight tube, and the first catalytic reaction proceeds inside the microchannels, and the resulting product is discharged through the second straight tube. The feed of the second catalytic reaction is supplied through one row of paired openings, and the reaction takes place on the outer side of the microchannels, then the product of the second reaction is discharged through the second row of paired openings. One of the two reactions is exothermic and the other one – endothermic.
The authors propose the use of the reactor for steam methane reforming, FT synthesis, and other processes. The increase in process efficiency, reduction in catalyst costs and production costs are also mentioned among the main advantages of the design.
The application/patent pair was published only in the Chinese Patent Office, in 2017 and 2019.
Image from CN106582468B
Patent CN107583577B published by Linyi University (CN) describes a method for using a micro reactor system to perform coupling reactions.
Feedstock for one exothermic and one endothermic reaction are preliminary mixed in mixing equipment, after which the reactants are introduced into the microreactor. The micro-reaction equipment is formed by serial connection of two microreactors with an automatic temperature control system. The microreactors have upper and lower heat-insulating and heating layers, as well as a micro-reaction layer consisting of upper and lower sealing plates and a micro-reaction plate between them. The micro-reaction plate includes two microchannels for two reactants, respectively. The microchannels are mutually arranged in the form of a zigzag or spiral. Each of the microchannels has a T- or L-shaped continuous mixing cavity. The wall of the microchannel opposite from the cavity includes a Y- or L-shaped baffle, the upper portion of the cavity is also equipped with a baffle in such a way that a gap is formed between the baffles. The inner walls of the microchannel and the cavity are coated with a catalyst for the corresponding reaction. The residence time of the reactants in the microreactor channel is 0.01-2 sec, the reaction pressure is 0.1-6 MPa.
The authors propose the reactor of the invention to be used for various kinds of reactions, including partial oxidation of methane, FT synthesis, steam methane reforming, and others. According to the text of the description, the invention provides an efficient use of energy in the reactor and a reduction in equipment costs.
The application/patent pair was published in CNIPA (CN) in 2018 and 2019.
Image from: CN107583577B
Production of hydrocarbons from syngas through the Fischer-Tropsch synthesis
A technical solution disclosed in the family of patent documents by Velocys Inc (US) represented by European patent EP2111438B1 can be considered as an example. According to the text of the document, steam and methane with a molar ratio of 0.5 to 6 are fed into a microchannel steam methane reforming (SMR) reactor to carry out the reaction in contact with catalysts, at a temperature of 600°C-1000°C, and a pressure of 5-25 atm. The microchannels of the SMR reactor are divided into the first part and the second part, with temperatures of 150-400ºC and 600-1000ºC, respectively. They are equipped with heat-exchange walls and are in thermal contact with the microchannels of the combustion reactor.
After the SMR, 50% of hydrogen is separated from the resulting intermediate product, which is combined with oxygen to create a combustible mixture that comes into contact with a catalyst and, as a result of the reaction, water and heat are released in the combustion stage. The released heat is sent to the SMR stage, and the water formed at the outlet is separated from the vapor phase for further use in the heat exchanger microchannels of the Fischer-Tropsch stage.
After the separation of a part of the hydrogen, the mixture obtained as a result of the SMR is sent to the Fischer-Tropsch (FT) synthesis stage, carried out at 180-300ºС and a pressure of 10-50 atm, to form paraffins or olefins. The heat from the FT synthesis is transferred to the microchannels of the heat exchanger. At the outlet from the FT stage, the unreacted gas phase is separated and sent to the second FT reactor to form paraffins or olefins. The microchannels of the second FT reactor are in thermal contact with the microchannels of the second heat exchanger, and heat from the operation of the second FT reactor is transferred to them.
The FT stage also generates tail gas, which contains H2, CO, CO2 and hydrocarbons. It passes through a hydrogen separator to provide a carbon-rich tail gas added to the feedstock, and a hydrogen-rich tail gas used as fuel.
The invention proposes additional stages of feedstock preparation, additional separation of the intermediate product and subsequent processing of the FT product. Catalysts used in the steam methane reforming, combustion, and Fischer-Tropsch synthesis stages are also described.
The invention is aimed at solving the problems associated with the emissions resulting in the process, production of large amounts of contaminated water, and low process efficiency.
Documents in this patent family were published from 2008 to 2015 in US EP RU CN AU CA BR WO JP, the family contains 17 documents in total.
Image from: EP2111438B1
US8173083B2 patent by CompactGTL (GB) can be considered as another example from this category of documents. The inventors propose "…a compact catalytic reactor defining a multiplicity of first and second flow channels arranged alternately in the reactor, for carrying first and second fluids, respectively, wherein at least the first fluids undergo a chemical reaction; each first flow channel containing a removable gas-permeable catalyst structure incorporating a metal substrate, the catalyst structure defining flow paths therethrough; wherein the catalyst structure incorporates a multiplicity of projecting resilient strips which support the catalyst structure spaced away from at least one adjacent wall of the channel. The resilient strips may be projecting lugs, attached to the metal substrate at one end. Preferably each catalyst structure incorporates resilient strips projecting in opposite directions, so that the catalyst structure is spaced away from both opposed adjacent walls of the channel. Where chemical reactions are to take place in both the first and second flow channels, then the second flow channels would also contain a removable gas-permeable catalyst structure incorporating such projecting resilient strips."
According to the inventors, the system has two reactors, the first of which is designed for steam methane reforming with the production of synthesis gas, while the second one – for Fischer-Tropsch synthesis. The authors indicate that the preferred depth of the channels in the FT reactor is less than 10 mm, and in the steam reformer - less than 5 mm. According to the description of the document, the design of the invention allows to reduce the pressure forces in individual elements and to ensure ease of spent catalyst replacement.
17 documents of this patent family were published in US AU CA CN EA AU BR EP GB NO WO TW between 2006 and 2013.
Image from: US8173083B2
Another patent from this group, US10974219B2 from BD Energy Systems LLC (US), describes a micro reformer device containing a radiant section, a combustion chamber and a convection section. The radiating section includes longitudinally-placed horizontal tubes with a structured reforming catalyst, a refractory lining for heat transfer to the horizontal tubes, and baffles for directing the flow of flue gases across the horizontal tubes for convectional heat transfer. The baffles comprise hexagonal blocks and consist of transverse ceramic walls spaced apart from each other along the radiant section, and having a first set of openings to support the horizontal tubes and a second set of openings for the crossflow of flue gases. The combustion chamber is oriented transversely with respect to the radiant section and supplies flue gas into it from a burner that provides flameless combustion or is located at a sufficient distance from the tubes. Flue gases from the radiant section pass through the transversely oriented convection section, that it is connected to a preheater for the air supplied to the burner and a feed gas preheater in the form of a plurality of coils with crossovers. The reformer device also includes horizontal tube effluent temperature control systems consisting of temperature sensors and valves and located between the feed gas manifold and the coils, in order to supply the feed gas to the corresponding coil depending on the measured effluent temperature.
The reformer device includes a heat transfer loop through the convection heat recovery section for use in another process such as FT synthesis.
The claims of the document also describe other working elements of the system and options for the mutual placement of the system modules. Among the advantages of the invention, the authors mention the provision of cost-effective, small-scale design and simplification of the assembly, transportation and installation of the system.
The family contains 6 documents published from 2019 to 2021 in US AU CA EP WO.
Image from: US10974219B2
For more information on the inventions in the field of small-scale GTL and patent research methodology, please visit aenert.com.