Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B15/00—Peroxides; Peroxyhydrates; Peroxyacids or salts thereof; Superoxides; Ozonides
  • C01B15/01—Hydrogen peroxide
  • C01B15/022—Preparation from organic compounds
  • C01B15/023—Preparation from organic compounds by the alkyl-anthraquinone process

Definitions

• the present invention relates to a process for the manufacture of hydrogen peroxide by an AO-process, e.g. a process wherein the manufacture of hydrogen peroxide takes place in an anthraquinone loop process.
• it is related to a manufacture of hydrogen peroxide by an AO-process comprising using specific reactor types in the hydrogenation step and/or in the oxidation step.
• Hydrogen peroxide is one of the most important inorganic chemicals to be produced worldwide.
• the world production of hydrogen peroxide grew to 3.2 million metric tons (100 % H 2 0 2 ) in 2009.
• Its industrial applications include textile, pulp and paper bleaching, paper recycling, organic synthesis (propylene oxide), the manufacture of inorganic chemicals and detergents, environmental and other applications.
• the industrial application pulp and paper bleaching, mining or environmental applications are of particular interest.
• alkylanthraquinone is intended to denote 9,10-anthraquinones substituted with at least one alkyl side chain of linear or branched aliphatic type comprising at least one carbon atom. These alkyl chains usually comprise less than 9 carbon atoms and preferably less than 6 carbon atoms.
• alkyl- anthraquinones are 2-ethylanthraquinone, 2-isopropylanthraquinone, 2-sec- and 2-tert-butylanthraquinone, 1,3-, 2,3-, 1,4- and 2,7-dimethylanthraquinone, 2-iso- and 2-tert-amylanthraquinone, and mixtures thereof.
• alkylanthraquinones are disclosed e.g. in US 6,224,845.
• tetrahydroalkylanthraquinone is intended to denote alkyl-5,6,7,8-tetrahydro-9,10-anthraquinones substituted with at least one alkyl side chain as defined for the alkylanthraquinones.
• Alkylanthra- quinones with one alkyl substituent are also disclosed e.g. in GB 943 683.
• the first step of the AO process is the reduction in an organic solvent of the chosen quinone (alkylanthraquinone or tetrahydroalkylanthraquinone) into the corresponding hydroquinone (alkylanthrahydroquinone or tetrahydroalkylanthraquinone) using hydrogen gas and a catalyst.
• the mixture of organic sol- vents, hydroquinone and quinone species (working solution, WS) is then separated from the catalyst and the hydroquinone is oxidized using oxygen, oxygen- enriched air or air thus regenerating the quinone with simultaneous formation of hydrogen peroxide.
• the organic solvent of choice is typically a mixture of two types of solvents, one being a good solvent of the quinone derivative (for instance a mixture of aromatic compounds) and the other being a good solvent of the hydroquinone derivative (for instance a long chain alcohol). Hydrogen peroxide is then typically extracted with water and recovered in the form of a crude aqueous hydrogen peroxide solution, and the quinone is returned to the hydrogenator to complete the loop.
• a good solvent of the quinone derivative for instance a mixture of aromatic compounds
• hydroquinone derivative for instance a long chain alcohol
• Hydrogen peroxide production is performed by a few chemical companies that produce it in large scale plants as an up to 50-70 % by wt. (% by weight) concentrate in water. Because of the highly oxidative characteristics of that level of concentration hydrogen peroxide usually is adjusted to a 50 % by wt. concentration for safe handling and transport, and 70 % by wt. concentrates normally are used only for transport over large distance due to cost reasons. For safety reasons the hydrogen peroxide product is normally diluted to at least 50 % by wt. before application, but for most applications it will be applied in a concentration of below 15 % by wt.
• hydrogen peroxide is used in various concentrations depending on the application, e.g. in a variety of appli- cations hydrogen peroxide is used in a concentration of approximately 1-15 % by wt.
• Some particular examples of such hydrogen peroxide concentrations are, depending on the kind of industrial application, % by wt.: pulp bleaching 2-10 %; waste water oxidation 1-5 %; consumer products surface cleaning 1-8 %.
• the hydrogen peroxide concentration may be higher, e.g. in aseptic packaging typical concentrations may be 35 % or 25 %.
• Manifold variations of the AO-process are known in the state of the art regarding size, reactors, process conditions, and production capacity.
• hydrogen peroxide is produced in large-scale to mega-scale production facilities and the produced hydrogen peroxide product is then transported to a customer site requiring the use of H 2 0 2 in its own industrial processes.
• the large-scale to mega-scale H 2 0 2 production is burdened with concomitant capital costs, H 2 0 2 transportation and handling problems associated with said large-scale to mega-scale production schemes.
• mini- AO processes should be as flexible as possible with the abi- lity for quick start-up, shut-down and turnaround, and accommodating variability in production rates, and as simple and robust as possible to also allow for an end user friendly plant which stably runs in continuous operation with a minimum need of local (e.g. on customer site) technical and/or physical intervention.
• the invention provides for a process for production of hydrogen peroxide by the AO-process which comprises the following steps (a) to (c):
• the hydrogenation (a) of the at least one quinone compound is performed by mixing a working solution comprising the quinone compound with hydrogen or a hydrogen containing gas in one or more mini-channel (packed) reactors; and/or
• the oxidation (b) of the at least one hydroquinone compound is performed by mixing a working solution comprising the hydroquinone compound with oxygen or an oxygen containing gas in one or more mini-channel (packed) reactors;
• the AO-process using at least one of the said mini-channel reactors in the hydrogenation (a) and/or in the oxidation (b) is adapted to obtain an aqueous hydrogen peroxide solution which is at least partially ready to be used on the same industry site as the said AO-process, either directly after resulting from the extraction (c) or optionally after a storage on the same site, in another industrial process on the said industry site which involves the use of an aqueous hydrogen peroxide.
• the hydrogenation or oxidation reaction in the AO-process is commonly carried in bubble columns in state of the art processes. This reaction requires hydrogen or oxygen, respectively, at high partial pressure, to decrease the reactor volume. Compressed air is most commonly (industrially) used to obtain oxygen at high partial pressure. This increases the energy requirements of the AO-process.
• mini-channel reactors To improve the gas-liquid mass transfer the use of mini-channel reactors is already proposed in the prior art. These reactors show high mixing between WS (working solution) and air/oxygen, resulting in a high gas-liquid mass transfer and low reaction volume, with lower energy requirements. A lower reactor volume also represents an intrinsic enhancement in the safety of the plant.
• mini-channel reactors are already known in the prior art, also for use in the hydrogenation or oxidation of an AO-process, it was not evident from the prior art that mini-channel (packed) reactors are particularly suitable for the manufacture of hydrogen peroxide in decentralized AO-process plants, in particular AO-process plants installed on a "host" industrial site, e.g. a customer site, requiring aqueous hydrogen peroxide solutions in its processes, and that the mini-channel (packed) reactors can advantageously be used to obtain an aqueous hydrogen peroxide solution which is at least partially ready to be used on the same industry site as the said AO-process in another industrial process on the said industry site which requires the use of an aqueous hydrogen peroxide.
• mini-channel reactors are very suitable for small to medium scale AO-processes, compact and modular reactor assemblies for performing a complete AO-process, and/or for AO- processes which are devoid of a permanent (conventional) reversion or regeneration unit for the working solution; as particularly described in more detail below as preferred embodiments of the invention.
• mini-channel packed reactor or similar terms like "mini-channel reactor” or “mini-reactor” as used in the context of the invention, wherein hydrogen peroxide is produced by the method of effecting in a cyclic process of hydrogenation and oxidation of a working compound (AO-process), shall mean a reactor containing one or more mini-channels with a specific packing that provide a flow path for the working compound (typically in a working solution), and wherein said mini-channels or its flow paths, respectively, have a relevant cross sectional dimension which are (much) smaller than the longitudinal dimension, e.g.
• the mini-channels are normally longitudinal in arrangement; a mini- reactor may contain one or multiple mini-channels, as many as 1,000,000 mini- channels.
• the mini-channels may be linked, e.g., in series or in parallel or in other configurations or combinations.
• the dimensions may be same or differ- rent in the hydrogenation and the oxidation mini-channel reactor.
• the mini-reactor may employ single or, preferably multiple, flow path mini-channels with at least one cross-sectional dimension within the ranges given above. Preferably said dimensions are not smaller than 5 mm and more preferably at least equal or not smaller than 6 mm, and up to 15 mm.
• the diameter or largest cross-sectional mini-channel dimension is in the range of at least 6 mm x 6 mm to up 15 x 15 mm, and any desired range and square or rectangular cross-sectional dimension within said two values, e.g. the minimum value of 6 mm and the maximum level 15 mm.
• Fluid flow through the mini-channels is generally in a longitudinal direction, approximately perpendicular to the cross-sectional mini-channel dimensions referred to above.
• the longitudinal dimension for the mini-channel is typically within the range of about 3 cm to about 10 meters, preferably about 5 cm to about 5 meters, and more preferably about 10 cm to about 3 meters in length.
• the mini-channel network may have mini- channels whose dimensions vary within ranges up these sizes and that these preferred dimensions are applicable to the sections of the mini-reactor where the hydrogenation reaction or oxidation reaction, respectively, is carried out. Therefore, in such a mini-channel reactor either the hydrogenation or the oxidation, respect- ively, is performed and its cross sectional and longitudinal dimensions may depend on whether the mini-channel reactor is intended for use in the hydrogenation or in the oxidation step of the AO-process, and on the overall selected process conditions for each of said hydrogenation and oxidation step.
• mini-channel dimensions and overall length is normally based on the residen- ce time desired for the working solution in the hydrogenation mini-reactor or in the oxidation mini-reactor, respectively, and on the contact time desired for multiphase system, e.g. in case of hydrogenation of the (liquid) working compound (in the working solution) and the (gaseous) hydrogenation agent, in the presence of the (solid) hydrogenation catalyst.
• the mini-channels in the mini- reactor may also include inert packing, e.g., glass beads or the like.
• these may be in sections of the mini-reactor not occupied by the hydrogenation catalyst, to improve the mixing and mass transfer between the gas phase component(s), e.g., hydrogenation agent, and liquid phase component(s), e.g., working compound, introduced into the mini-reactor.
• gas phase component(s) e.g., hydrogenation agent
• liquid phase component(s) e.g., working compound
• the mini-channel cross section may be any of a variety of geometric configurations or shapes.
• the mini-channel cross section may be rectangular, square, trapezoidal, circular, semi-circular, ellipsoidal, triangular, or the like.
• the mini-channel may contain wall extensions or inserts that modify the cross-sectional shape, e.g., fins, etc.
• the shape and/or size of the mini-channel cross section may vary over its length. For example, the height or width may taper from a relatively large dimension to a relatively small dimension, or vice versa, over a portion or all of the length of the mini-channel.
• the present invention utilizing a mini-reactor, can be employed with working compounds known to the skilled person and conventionally used in large- to mega-scale in auto -oxidation processes (AO-processes).
• the process of the invention is suitable for hydrogenating alkyl anthraquinones and/or alkyl hydroanthraquinones to their corresponding alkyl anthrahydroquinones and/or alkyl hydroanthrahydroquinones and/or oxidizing the alkyl anthrahydroquinones and/or alkyl hydroanthrahydroquinones to their corresponding alkyl anthraquinones and/or alkyl hydroanthraquinones.
• the invention is also suitable for AO- processes utilizing compositions of two or more different anthraquinones and/or their corresponding ring hydrogenated derivatives to their corresponding anthrahydroquinones and/or for auto-oxidizing said hydrogenated anthrahydroquinones and/or the corresponding ring hydrogenated derivatives to yield the desired hydrogen peroxide product.
• a preferred embodiment of the invention is a cyclic method for the production of hydrogen peroxide by the steps of catalytically hydrogenating a working compound to yield a hydrogenated working compound; oxidizing the hydrogenated working compound to produce hydrogen peroxide; separating the resulting hydrogen peroxide from the oxidized working compound and recover- ing the hydrogen peroxide in an aqueous solution; and recycling the oxidized working compound to the hydrogenation step.
• the invention is particularly adapted to the cyclic auto-oxidation production of hydrogen peroxide (AO-process), in which a suitable organic working compound is catalytically hydrogenated.
• the hydrogenated working solution withdrawn from the hydrogenation react- or, which in an embodiment of the invention can be a hydrogenation mini-channel reactor, is thereafter auto -oxidized, which in an embodiment of the invention can take place in an oxidation mini-channel reactor, to yield hydrogen peroxide.
• the hydrogen peroxide product is recovered from the working solution, preferably by water extraction, and the working solution is then recirculated into the hydrogenation step.
• the present invention primarily aims at designing an optimized small- to medium-scale AO-processes (mini- AO scale), e.g. in regard of production capacity or plant size, which in particular can be installed at a remote site, e.g. a customer site utilizing hydrogen peroxide in its own processes.
• mini- AO scale small- to medium-scale AO-processes
• Such a small- to medium-scale AO-process (mini- AO scale concept) for hydrogen peroxide production is subject to special requirements regarding hydrogenation and oxidation steps, as for example: the reaction efficiency which must be as high as possible to decrease investment cost; the installation area which might be limited due to installation at customer site; the process control which should be remotely monitored with a minimum local intervention; the process safety which is higher than for the standard technology due to installation at a customer site and high automation.
• the special requirements described above are not fulfilled by the standard hydrogenation and oxidation reaction technologies employed in large- to mega-scale hydrogen peroxide production plants.
• the present invention has developed a new process and reactor type for this application. The development is based on the mini-channel technology filled with special packing structures.
• mini-channel packed reactor This technology is referenced in the context of this invention as mini-channel packed reactor, as already defined further above.
• micro-channel reactors as such in the oxidation or hydrogenation of an AO-process is known in the prior art, but is less suitable than the mini-channel (packed) reactor used according to the present invention.
• the PCT-application WO 2007/027767 A2 discloses a pro- cess wherein hydrogen peroxide is prepared by an auto -oxidation method via hydrogenation in a micro-reactor.
• the dimensions of the mini-reactor are larger than in the above PCT-application which is directed to the smaller dimensions of a micro-reactor.
• the micro-reactor in the named PCT-application is deemed more suit- able for a lab-scale process
• the mini-reactor according to the present invention is more suitable for an industrial process, e.g. an industrial mini-scale process.
• a working solution containing a reactive carrier compound is hydrogenated with hydrogen in a mini-reactor and is subsequently auto- oxidized, which optionally may take place in a mini-reactor as described herein after but can take place in any other oxidation reactor, to produce hydrogen peroxide.
• the mini-reactor employed in the present invention allows on its internal surface for the optimum catalyst deposition techniques that enhance reactant selectivity. Uniform metal catalyst distribution and deposition on the mini-reactor walls can be employed, as an alternative to coating of the catalyst on a porous substrate, to avoid metal agglomeration common on porous substrates, e.g., alumina or silica-alumina.
• optimum phase and pore diameter catalyst properties can be achieved for the hydrogenation catalyst employed in a mini- reactor. These enhanced properties reduce sub-optimal contact or residence time between the anthraquinone reactant molecule or anthrahydroquinone molecule (or other reactive compound employed) and catalyst surface and also serve to minimize the amount of expensive metal catalyst required. Accordingly, the AO- process of the present invention can be performed as described in a hydrogenation mini-reactor containing at least one inlet, as an entrance for the joint or separate introduction of the working compound and hydrogenation agent into the mini-reactor mini-channels, and at least one exit, for withdrawal of the hydrogenated working compound.
• the mini-channel configurations can be linked to one or more entrances and/or exits via manifold or header channels.
• the hydrogenation agent may be introduced into the hydrogenation mini-reactor in admixture with the introduced working compound or separately, via a separate inlet that connects directly or indirectly with one or mini-channels carrying the introduced working compound.
• the mini-channel reactor may contain other mini-channel process control aspects besides entrance(s) and exit(s), such as valves, mixing means, separation means, flow re-redirection conduit lines, that are in or a part of the mini-channel system.
• the mini-channel reactor may also comprise heat exchange and heat flux control means, such as heat exchange conduits, chambers or mini- channels, for the controlled removal or introduction of heat to or from the solution or fluid flowing through the mini-channel network.
• the mini-reactor may also contain process control elements, such as pressure, temperature and flow sensors or control elements. Operating conditions, e.g., temperature and pressure, within the hydrogenation mini-channel reactor are generally within the ranges normally established for large- to mega-scale hydrogenation reactions carried out in AO-processes.
• the WO 2007/027785 A2 discloses a process wherein hydrogen peroxide is prepared by an auto-oxidation method via oxidat- ion in a micro-reactor.
• the dimensions of the mini- reactor, as described in more detail above, are larger than in the above PCT- application which is directed to the smaller dimensions of a micro -reactor.
• the mini-reactor according to the present invention is more suitable for an industrial process, e.g. an industrial mini-scale process.
• a working solution containing a reactive carrier compound is hydrogenated with hydrogen in a first step, which optionally may take place in a mini-channel reactor as described herein before but can take place in any other hydrogenation reactor, and is subsequently oxidized in a mini-channel reactor to produce hydrogen peroxide.
• the AO-process of the present invention can be performed with an oxidation mini-channel reactor containing at least one inlet, as an entrance for the joint or separate introduction of the working compound and oxidation agent into the mini-reactor mini-channels, and at least one exit, for withdrawal of the oxidized working compound and hydro- gen peroxide product.
• the mini-channel configurations can be linked to one or more entrances and/or exits via manifold or header channels.
• the oxidizing agent may be introduced into the oxidation mini-reactor in admixture with the introduced working compound or separately, via a separate inlet that connects directly or indirectly with one or mini-channels carrying the introduced working compound.
• the mini-channel reactor may contain other mini-channel process control aspects besides entrance(s) and exit(s), such as valves, mixing means, separation means, flow re-redirection conduit lines, that are in or a part of the mini-channel system.
• the mini-reactor may also contain heat exchange and heat flux control means, such as heat exchange conduits, chambers or mini- channels, for the con- trolled removal or introduction of heat to or from the solution or fluid flowing through the mini-channel network.
• the mini-reactor may also contain process control elements, such as pressure, temperature and flow sensors or control elements. Operating conditions, e.g., temperature and pressure, within the oxidation mini-reactor are generally within the ranges normally established for large- to mega-scale hydrogenation reactions carried out in AO-processes, and e.g., as also described in the above named PCT-application.
• the mini-channel packed reactor of the present invention shall be described in some more detail. It consists of a reactor containing a number of parallel channels ranging from 1 to 1,000,000 preferably ranging from 1,000 to 100,000, and each channel having a cross-section dimension (D) ranging from 5 mm to 20 mm preferably between 5 and 15 mm.
• D cross-section dimension
• the length of the channels is in the range of 0.05 m to 20 m.
• Several materials can be used in the construction of the reactor, like aluminum, stainless steel (grades 304, 316, 304L, 316L), PTFE and ceramic or any kind of material that shows chemical compatibility with the hydrogen peroxide production typical chemicals (e.g. organic solvents, H 2 0 2 , water, oxygen, hydrogen, etc.), suitable mechanical properties at operational temperature and pressure of the reactor.
• the preferred materials are aluminum and stainless steel if the reaction is coupled to heat removal.
• the packing used to fill the mini-channel packed reactor can be classified as inert packing and catalytic packing according to the function of the packing in the reaction. While not wished to be bound by theory, a more details of the functioning of an inert packing and a catalytic packing shall be given as follows.
• the inert packing acts to improve the gas-liquid mass transfer by supplying the gas-liquid mixture with energy used to break the gas bubbles into small bubbles resulting in a very high interface between gas and liquid.
• the high gas- liquid mixing generated by the packing also improves diffusion of reaction com- ponents.
• the inert packing can be used as a pre-mixer of H 2 (hydrogen) and working solution in the hydrogenator, placed before the catalytic bed and also to improve the oxidation reaction by intensifying the contact of 0 2 (oxygen) and working solution.
• the catalytic packing provides the presence of a catalyst metal dispersed on the packing which improves the reaction kinetics by a decrease in the reaction activation energy.
• the catalytic packing is used in the hydrogenator in order to enable the hydrogenation reaction.
• each, the catalytic and inert packing individually can be chosen according to the desired process features like pressure drop and mixing requirements, which is related to the reaction rate.
• types of packing shape can be employed, for example, like spherical, cylindrical, rings, disks, granulates, hollow extrudates, but is not limited to these examples.
• the intensity of the mixing is proportional to the pressure drop and inversely proportional to the void fraction of the mixing.
• the packing particle size also influences the degree of mixing and pressure drop.
• a typical packing largest dimension can be in the range of 0.1 mm to 3 mm, preferably between 0.5 and 1.5 mm, especially for cases of spherical, cylindrical, rings, disks, granulates, hollow extrudates.
• the packing dimension can be in the range of from mesh 6 to mesh 170, preferably in the range of from mesh 12 to mesh 35.
• the packing material for the catalytic packing (hydrogenation) can be chosen among all suitable catalyst support materials, like silica-gel, alumina, sodium silico aluminated, ceramic, but is not limited these materials.
• the selection of the packing needs taking into account the compatibility of the packing with H 2 0 2 .
• the inert packing material can be glass, PTFE, stainless steel, ceramic, but is not limited to these.
• the gas and liquid distribution among the channels should be efficient enough to avoid excess of hydrogenation in the case of the catalytic packing (hydrogenation sector) and avoid excess of non-reacted oxygen in the oxidation reactor.
• the presence of a liquid distributor is recommended in order to avoid mal-distribut- ion among the channels.
• liquid distributors There are several types of liquid distributors that can be employed in the mini-channel packed reactor technology that can be described as "perforated tray”, “multiport chimney”, “bubble cap”, “vapor-lift tube”, but is not limited to these.
• the mini-channels can be continuous or alternating segments of mini-channels and mixing zones.
• the intermediate mix- ing zones can be used also as reagents injection zone or product removal zone to improve reaction and hydraulic parameters.
• the reaction unit can be a pair liquid distributor/packed mini-channel reactor, and in another embodiment the reactor can comprise 1 to 10 units, preferably of from 1 to 5 units.
• Recovery of the resulting hydrogen peroxide produced in the oxidation step of the AO-process according to the present invention is normally carried out via water extraction of the working solution effluent stream from the oxidation reactor.
• Conventional extraction techniques and equipment may be used for the hydrogen peroxide recovery, and these techniques are well-known to those skilled in the art.
• Other hydrogen peroxide recovery techniques are also possible, for separating the hydrogen peroxide from the working solution, but water extraction is preferred.
• the oxidation according to the invention in a mini-channel reactor is performed in absence of water. Otherwise, if the oxidation according to the invention in a mini-channel reactor is performed in, a non-preferred manner in the presence of water, there might be need to equip the AO-process facility with means to break down emulsion.
• the invention relates to a process for production of hydrogen peroxide by the AO-process, characterized in that the oxidation (b) of the at least one hydroquinone compound is performed by mixing a working solution comprising the hydroquinone compound with oxygen or an oxygen containing gas in a mini-channel reactor in the presence of water.
• AO-process for production of hydrogen peroxide comprises technical means for coalescing and/or breaking down emulsions of the working solution and water, preferably technical means for coalescing and/or breaking down emulsions of the working solution and water combined with the extraction step (c) of the AO-process.
• the hydrogen peroxide is preferably extracted from the working solution in a separate extraction step (c), which may be performed in a conventional extraction column under conditions well-known to those skilled in the art.
• the hydrogen peroxide can be extracted from the working solution either in a conventional separate extraction step (c), which may be performed in a conventional extraction column under conditions well-known to those skilled in the art, and/or the extraction can take place at least partially during the oxidation steps (so-called "oxido-extraction").
• Oxido-extraction means addition of water already in the oxidizer during the production of hydrogen peroxide (e.g. not only in the subsequent extractor).
• oxidation and extraction is described in US 5,725,837, which hereby is incorporated by reference, but which combination does not employ mini- channel reactors.
• the recovered hydrogen peroxide product, in the aqueous extract, according to the invention will then be adjusted, as desired, to a suitable concentration for its subsequent use in an industrial application, using concentration techniques and equipment conventionally used in the production of hydrogen peroxide.
• adjusting the hydrogen peroxide concentration in the aqueous hydrogen peroxide product will not employ any distillation to higher concentrates (e.g. such of 50-70% by wt. as indicated in the introduction) , but is merely limited to adjusting the concentration to hydrogen peroxide product recovered from the AO-process according to the invention to comply with an aqueous ready-to-use hydrogen peroxide product depending on the application and requirement at the application (e.g. host or customer) site, e.g.
• hydrogen peroxide as used in a concentration of approximately 1-15 % by wt.
• Some particular examples of such hydrogen peroxide concentrations are, depending on the kind of industrial application, % by wt.: pulp bleaching 2-10 %; waste water oxidation 1-5 %; consumer products surface cleaning 1-8 %.
• the hydrogen peroxide concentration may be higher, e.g. in aseptic packaging typical concentrations may be 35 % or 25 %.
• various stabilizers may be added to the recovered product, to minimize hydrogen peroxide decomposition, as is well known in the art.
• the present invention primarily aims at small- to medium-scale AO-processes (mini- AO scale), e.g. in regard of production capacity or plant size.
• mini- AO scale small- to medium-scale AO-processes
• the invention is suitable for AO- process of mini- AO scale in a "modular concept" and/or "decentralized facilities with remote control”.
• the invention is very suitable for AO-processes without or only with intermittent or periodical reversion (regeneration) of the working solution after certain time (periods or intervals).
• the invention is suitable for an AO-process that shall work without reversion (regeneration) of the working solution for certain, especially prolonged, period of time or for AO-process wherein the reversion of the working solution takes place only intermittently or periodically.
• the invention relates to a process for production of hydrogen peroxide by the AO-process, characterized in that the mini-channel reactor in the hydrogenation (a) and/or the oxidation (b) is adapted to a small to medium scale AO-process wherein the steps of (a) hydrogenation, (b) oxidation and (c) extraction are performed in an reactor system which is designed as a compact modular system of a hydrogenation, an oxidation and an extraction unit.
• the mini-channel reactor in the hydrogenation (a) and/or the oxidation (b) is adapted to a small to medium scale AO-process wherein the steps of (a) hydrogenation, (b) oxidation and (c) extraction are performed in an reactor system which is designed as a compact modular system of a hydrogenation, an oxidation and an extraction unit.
• skid mounted module comprising at least one hydrogenator (hydrogenation reactor) to hydrogenate the anthraquinone in the working solution, denoted as skid 1 (hydrogenation skid);
• skid mounted module comprising at least one oxidizer (oxidation reactor) to oxidize the hydrogenated anthraquinone with oxygen to form hydrogen peroxide, denoted as skid 2 (oxidizer skid);
• skid mounted module comprising at least one means to compress air (process air compressor), denoted as skid 3 (process air compressor skid), to feed oxygen, in particular oxygen from the air, into an oxidizer of skid 2, and in case of presence of skid 3 a further skid mounted module comprising at least one means to recover the solvent (solvent recovery unit), denoted as skid 4 (solvent recovery unit skid), in particular if oxygen from the air is used to feed oxygen into an oxidizer of skid 2; - a skid mounted module comprising at least one means to extract the hydrogen peroxide from the working solution (extraction unit), denoted as skid as skid 5 (extraction skid);
• skid 6 a skid mounted module, denoted as skid 6, comprising at least one means to deliver hydrogen peroxide solution to the point of use and/or optionally to a storage tank optionally with additional means for adjusting the hydrogen peroxide concentration.
• the hydrogenator (skid 1) or the oxidizer (skid 2) independently of each other or both can be a mini-channel reactor as described above according to the present invention. Therefore, in this embodiment the invention relates to a process for production of hydrogen peroxide by the AO-process, characterized in that the mini-channel reactor in the hydrogenation (a) and/or the oxidation (b) is a skid mounted component of a modular mini- AO-process plant concept.
• the AO-process of the present invention is very suitable not only for conventional industrial large- to mega-scale AO-processes, but particularly also for small- to medium-scale AO-processes. Therefore, the invention also relates to an anthraquinone process for the production of hydrogen peroxide according to the present invention wherein the anthraquinone process is a small-to-medium scale AO-process (mini- AO process) which is run with a production capacity of hydrogen peroxide (as 100 %) of up to 20 ktpa, preferably with a production capacity of hydrogen peroxide of up to 15 kilo tons per year, and more preferably with a capacity of up to 10 ktpa, and even more preferably with a capacity of up to 5 ktpa.
• a production capacity of hydrogen peroxide (as 100 %) of up to 20 ktpa, preferably with a production capacity of hydrogen peroxide of up to 15 kilo tons per year, and more preferably
• the lower capacity may be any capacity of e.g. 1 ktpa, 2 ktpa, 3 ktpa or 4 ktpa, and each of these lower capacities may be combined with any of the preceding upper capacities to a respective capacity range.
• the AO-process according to the present invention is run with a production capacity of hydrogen peroxide (as 100 %) in the range of 1 to 20 ktpa, or 2, 3, 4 or 5 ktpa to 20 ktpa; preferably in the range of or 2, 3, 4 or 5 ktpa to 15 ktpa; more preferably in the range of or 2, 3, 4 or 5 ktpa to 10 ktpa; and most preferably in the range of or 2, 3 or 4 ktpa to 5 ktpa.
• the invention can be employed in any type and size of the AO- process for the manufacture of hydrogen peroxide, it is advantageously used in, especially in small-to-medium scale hydrogen peroxide production AO-processes and/or, hydrogen peroxide production AO-processes that do not have a perma- nent (conventional) regeneration of the working solution.
• a small-to-medium scale AO-process for the production of hydrogen peroxide without a revers- ion (regeneration) unit is described in the PCT patent application PCT/EP2012/- 069414 (filed on October 2, 2012), which hereby is incorporated by reference.
• the AO-process of the present invention is very suitable not only for conventional industrial AO-processes which involve a permanent regeneration step routine for the working solution, but particularly also for AO- processes which are devoid of such a permanent regeneration step routine.
• the invention also relates to an anthraquinone process for the production of hydrogen peroxide according to the present invention
• the anthraquinone process is an autoxidation process (AO-process) which is run without a conventional reversion unit for regenerating the working solution, and characterized in that the working solution and/or the catalyst are replaced and/or treated for regeneration or reactivation only intermittently with a low frequency, preferably characterized in that the working solution and/or the catalyst are replaced and/or treated for regeneration or reactivation only periodically after periods of at least 3 months, preferably at least 6 month, more preferably at least 9 months, and most preferred at least 12 months.
• AO-process autoxidation process
• a small-to -medium scale AO-process which is run with a capacity as indicated hereinbefore
• a small- to-medium scale AO-process which is run with a capacity of up to 20 ktpa, preferably of up to 15 ktpa, more preferably of up to 10 ktpa, and most preferably of up to 5 ktpa, or with any other capacity or capacity range as indicated hereinbefore, and/or particularly in case the AO-process is devoid of a reversion (regeneration) unit for the working solutions
• the present invention is also very useful if such, e.g.
• the AO-process is remotely controlled.
• a small-to -medium scale AO-process for the production of hydrogen peroxide without a reversion (regeneration) unit is described in the PCT patent application PCT/EP2012/069408 (filed on October 2, 2012), which hereby is incorporated by reference.
• the present invention also relates to pro- cess for production of hydrogen peroxide by the AO-process, characterized in that the mini-channel reactor in the hydrogenation (a) and/or the oxidation (b) is a component of a mini- AO-process plant in which is remotely controlled such that the AO-process units for the steps (a) to (c), optionally with further ancillary AO-process units as appropriate, together constitute a hydrogen peroxide pro- duction satellite site in which one or more of said AO-process units are equipped with one or more sensors for monitoring one or more AO-process parameters at the hydrogen peroxide production satellite site, said sensors being interconnected with one or more first computers at the hydrogen peroxide production satellite site, said first computers being linked via a communication network to one or more second computers in a control room located at a control center site being different and remote from the hydrogen peroxide production satellite site, and wherein the hydrogen peroxide production satellite site is remotely controlled by said second computers in the control room of the control center site.
• the mini-channel packed reactor was evaluated as an intensified oxidation reactor for the oxidation of hydrogenated anthraquinones in a hydrogen peroxide production process.
• the trials were, in a non-continuous system (bench tests), using a single tube of 5 mm diameter and 500 mm length filled with 0.8 and 2.0 mm glass beads packing.
• the H 2 0 2 productivities achieved in the mini- channel packed reactor were found to be between 1100 and 2100 kg H 2 0 2 /m 3 reactor/hr ("hr” or alternatively "h” means "hour"), for packing diameter of 2 mm and 0.8 mm respectively, using a pure oxygen stream as the oxidation medium.
• the reactor productivity of an industrial bubble column oxidizer which is the classical technology employed in the AO process, is around 50 kg H 2 0 2 /m 3 reactor/hr using air and 350 kg H 2 0 2 /m 3 reactor/hr for oxygen.
• the result of these trials showed that the oxidation step in the AO process can be substantially intensified, resulting in much smaller equipment sizes and process inventories (safety aspects).
• the oxidation mini-channel packed reactor was chosen as the main sector for process intensification, as classical AO-process oxidizers are normally very large in size, as well as capital and energy intensive.
• One of the chosen technologies was the use of mini-channel packed reactors, in combination with oxygen enrichment. An experimental set up of such an oxidation mini-channel packed reactor is described below in more detail.
• the experimental set-up used for the experiments comprised one reactor for oxidation reaction enhanced by the presence of packing (with glass beads).
• a brief description of the reactor set-up follows: Packed mini-channel, reactor diameter ID 5 mm, being filled with glass spherical packing of 800 micrometers and 2000 micrometers diameter.
• inlet zone At the bottom of the reactor there was an enlarged chamber called "inlet zone” to decrease liquid velocity and to avoid higher pressure fluctuations.
• the transition zone, between the inlet zone and the capillary had a conical shape and the purpose was also to decrease pressure fluctuations.
• the oxygen entered the system in the bottom region of the inlet zone and was injected directly inside the mini-channel through the use of the syringe needle.
• the "outlet zone” was also designed as an enlargement of the mini-channel to decrease pressure fluctuations caused by the detachment of the gas bubbles from the capillary. To stop the oxidation, excess nitrogen was injected at the top of the reactor to dilute the unreacted oxygen. The oxidized working solution and the diluted oxygen stream could exit through a side nozzle.
• the flow control of the hydrogenated working solution was done by an automatic titration device, which could deliver a working solution with continuous flow rate with lower values, as low as 0.1 ml/min.
• the orifice for oxygen injection was adapted from an AISI 304 chromatograph syringe needle.
• test objective was reacting the highest working solution flow rate limited by the pressure drop and to achieve almost total conversion. This conversion was first observed visually and then determined by lab analysis. The reactor productivity was compared to the empty tube trial.
• G/L Interface & Mixing Due to the small clearance between the glass beads, the bubbles with dimensions higher than these spaces break into micro- bubbles, were leading to a higher G/L interface. Another positive aspect was the lower surface tension between the working solution and oxygen, which contributed to the formation of micro-bubbles and to an increase of mass transfer surface. A further feature of the packed mini-channel was the fluid mixing enhancement, which could contribute to higher diffusion rates of chemical species resulting in a faster reaction.

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• Oxygen, Ozone, And Oxides In General (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2015
  • 2015-08-19 WO PCT/EP2015/069007 patent/WO2017028911A1/en active Application Filing
  • 2015-08-19 BR BR112018003016A patent/BR112018003016A2/pt not_active Application Discontinuation

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