Olefin hydration process

Abstract

The invention relates to the field of organic synthesis, in particular to an olefin hydration method. The method comprises the following steps: carrying out hydration reaction on an olefin raw material and water in the presence of a first auxiliary agent, an optional second auxiliary agent and a catalyst, the first auxiliary agent comprises an emulsifier. According to the present invention, the olefin raw material contacts the first auxiliary agent containing the emulsifier, the second auxiliary agent, the catalyst and the water so as to effectively enhance the intersolubility of the olefin such as butene and water, such that the olefin and the water present the emulsified state, and the one-way conversion rate of the olefin is substantially improved.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and particularly to a method for olefin hydration. Background Art

[0002] The olefin hydration reaction is a process commonly used in industry for preparing alcohols from olefins, which is mainly divided into direct hydration method and indirect hydration method. In the traditional indirect hydration process, after the olefin reacts with sulfuric acid to form a sulfate ester, hydrolysis is carried out to obtain the corresponding alcohols. However, there are problems such as many by-products, the need for a large amount of sulfuric acid, corrosion of equipment caused by sulfuric acid, reuse treatment of sulfuric acid, and waste liquid treatment. The direct hydration method is to directly hydrate the olefin with water to produce the corresponding alcohol under high pressure conditions using a strongly acidic resin or heteropolyacid as a catalyst. However, since olefins are non-polar compounds and water is a strongly polar compound, the mutual solubility between the two is small, resulting in a low conversion rate of olefins. In industry, the pressure required for the olefin hydration reaction usually reaches above 6 MPa, aiming to increase the solubility of olefins in water.

[0003] The olefin hydration reaction process is a typical liquid (olefin)-liquid (water) mass transfer reaction system, and the reaction rate and conversion rate are greatly affected by liquid-liquid mass transfer. This is mainly because the mutual solubility between the two liquid phases of olefin and water is small, which restricts the reaction efficiency and production capacity of the olefin hydration process. In the prior art, static mixing is generally used for mixing. During the reaction process, due to the large droplet size (generally in millimeters) of the conventional mixing method, the state is unstable, the contact surface area between the two phases is large and easy to phase separate, resulting in a very slow mass transfer reaction rate. Therefore, a series connection of multiple reactors is generally used, which has problems such as low single-pass conversion rate of raw materials, long residence time, easy phase separation, high energy consumption of the device, and low efficiency.

[0004] Typical olefin hydration reactions are the hydration of cyclohexene to cyclohexanol and the hydration of n-butene to sec-butanol. In the process of the hydration of cyclohexene to cyclohexanol, the reactor form of the cyclohexene direct hydration production device currently used in industry is a two-stage series full-mix reactor, with a single-pass conversion rate of only 9% and a selectivity of 99%. The single-pass conversion rate of the cyclohexene hydration reaction is low, and a large amount of unreacted cyclohexene and cyclohexanol are separated by multiple cycles of rectification, resulting in high energy consumption. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem of low olefin conversion rate existing in the prior art olefin hydration technology, and provide a method for olefin hydration, which has the characteristic of high olefin conversion rate.

[0006] To achieve the above purpose, on the one hand, the present invention provides a method for olefin hydration, which includes: carrying out a hydration reaction between an olefin raw material and water in the presence of a first auxiliary agent, optionally a second auxiliary agent, and a catalyst; the first auxiliary agent contains an emulsifier.

[0007] Through the above technical solution, the present invention has the following advantages:

[0008] By contacting an olefin raw material with a first auxiliary agent, a second auxiliary agent, a catalyst, and water containing an emulsifier, the present invention effectively enhances the mutual solubility of an olefin such as butene and water, makes the olefin and water present an emulsified state, and greatly improves the single-pass conversion rate of the olefin. Description of the Drawings

[0009] Figure 1 It is a device diagram and a process flow diagram according to a preferred embodiment of the present invention;

[0010] Figure 2 It is an internal structure diagram of a microchannel reaction unit according to a preferred embodiment of the present invention.

[0011] Description of the Reference Numerals

[0012] 1 - First raw material tank, 2 - Second raw material tank, 3 - Third raw material tank, 4 - Microchannel reactor, 5 - First raw material collection tank, 6 - First metering pump, 7 - Second metering pump, 8 - Third metering pump, 9 - Heating layer, 10 - Insulation layer, 11 - Olefin, 12 - Auxiliary agent aqueous solution, 13 - Catalyst aqueous solution, 14 - Mixed aqueous solution of auxiliary agent and catalyst, 15 - First reaction product, 16 - First organic phase, 17 - First aqueous phase. Detailed Embodiments

[0013] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0014] The present invention provides a method for olefin hydration, the method comprising: performing a hydration reaction on an olefin raw material and water in the presence of a first auxiliary agent, optionally a second auxiliary agent, and a catalyst; the first auxiliary agent contains an emulsifier.

[0015] By contacting an olefin raw material with a first auxiliary agent, a second auxiliary agent, a catalyst, and water containing an emulsifier, the present invention effectively enhances the mutual solubility of the olefin and water, makes the olefin and water present an emulsified state, and greatly improves the single-pass conversion rate of the olefin.

[0016] According to a preferred embodiment of the present invention, the HLB value of the emulsifier is 10 - 20.

[0017] According to a preferred embodiment of the present invention, the emulsifier is selected from at least one of Tween, nonylphenol polyoxyethylene ether compounds, and alkylphenol polyoxyethylene ether compounds, preferably at least one of Tween 20, Tween 40, Tween 60, Tween 80, nonylphenol polyoxyethylene ether-10, nonylphenol polyoxyethylene ether-15, and alkylphenol polyoxyethylene ether-10.

[0018] According to a preferred embodiment of the present invention, the first auxiliary agent further includes a water-soluble diol reagent with a carbon number ≥ 4.

[0019] According to a preferred embodiment of the present invention, the water-soluble diol reagent with a carbon number ≥ 4 is selected from at least one of diethylene glycol, triethylene glycol, polyethylene glycol 400, and polyethylene glycol 600;

[0020] According to a preferred embodiment of the present invention, the mass ratio of the emulsifier to the water-soluble diol reagent with a carbon number ≥ 4 in the first auxiliary agent is 50-90:50-10.

[0021] According to a preferred embodiment of the present invention, the second auxiliary agent is an inorganic acid, preferably the inorganic acid is selected from phosphoric acid and / or silicic acid.

[0022] According to a preferred embodiment of the present invention, the catalyst includes a heteropolyacid catalyst, preferably the heteropolyacid catalyst is selected from phosphomolybdic acid and / or tungstosilicic acid.

[0023] According to a preferred embodiment of the present invention, the olefin raw material contains C4-C6 olefins, preferably a raw material containing butene.

[0024] According to a preferred embodiment of the present invention, the method includes: contacting the olefin raw material with an aqueous phase containing a first auxiliary agent, a second auxiliary agent, and a catalyst to carry out a hydration reaction.

[0025] According to a preferred embodiment of the present invention, the content of the first auxiliary agent in the aqueous phase is 0.3-8 wt%, the content of the second auxiliary agent is 0.5-1.5 wt%, and the content of the catalyst is 15-40 wt%

[0026] According to a preferred embodiment of the present invention, the conditions of the hydration reaction include: temperature 150-200 °C; and / or pressure 5-15 MPa; and / or water-olefin molar ratio 2-8.

[0027] According to a preferred embodiment of the present invention, the method includes subjecting the organic phase stream obtained from the hydration reaction to a hydration reaction again, repeating 1-4 times.

[0028] According to a preferred embodiment of the present invention, the water-olefin molar ratio of the subsequent hydration reaction is 0.1-0.2 lower than that of the previous hydration reaction.

[0029] According to a preferred embodiment of the present invention, the method is carried out in a device, and the device includes: an olefin raw material feeding system, an aqueous phase feeding system, and a reaction separation system;

[0030] The reaction separation system includes alternately arranged microchannel reaction units and oil-water two-phase separation units;

[0031] The microchannel reaction unit includes at least two, preferably 2-4, microchannel reaction structures arranged in series and / or in parallel in sequence, and is used for mixing and hydrating the olefin raw material and the aqueous phase; the reaction structure includes an olefin raw material feeding main pipe and a product discharging main pipe, and a serpentine reaction pipe located between the olefin raw material feeding main pipe and the product discharging main pipe. There are at least two serpentine reaction pipes, and both ends of each serpentine reaction pipe are respectively formed into a feeding end and a discharging end. Among them, the discharging end of each serpentine reaction pipe is communicated with the product discharging main pipe, and the feeding end of each serpentine reaction pipe extends to the olefin raw material feeding main pipe to form a feeding branch pipe. Among them, along the extending direction, the included angle between the axes of the feeding branch pipes of any serpentine reaction pipe is not less than 20°, preferably 30-120°, and a radial aqueous phase feeding pipe is communicated on any feeding branch pipe; the olefin raw material feeding system is communicated with the first microchannel reaction unit along the material flow direction; the aqueous phase feeding system is communicated with each microchannel reaction unit.

[0032] According to a preferred embodiment of the present invention, there are 2-4 serpentine reaction pipes.

[0033] According to a preferred embodiment of the present invention, any arc of any serpentine reaction pipe is the short arc intercepted by the corresponding circle at the diameter at the place. By adopting the foregoing preferred scheme, the full mixing of raw materials can be further realized, and the reaction efficiency can be improved.

[0034] According to a preferred embodiment of the present invention, any arc of each serpentine reaction pipe is the same, and preferably any arc of each serpentine reaction pipe is the same.

[0035] According to a preferred embodiment of the present invention, the diameter of the circle corresponding to any arc of any serpentine reaction pipe is twice the equivalent diameter of the serpentine reaction pipe.

[0036] According to a preferred embodiment of the present invention, the short arcs on any serpentine reaction pipe are connected in a peak-valley tangent manner, and the number of short arcs ≥ 3. By adopting the foregoing preferred scheme, the full mixing of raw materials can be further realized, and the reaction efficiency can be improved.

[0037] According to a preferred embodiment of the present invention, the equivalent diameter of the feeding main pipe is 1-8 mm.

[0038] According to a preferred embodiment of the present invention, the equivalent diameter of the feed branch pipe is 0.5 - 4 mm.

[0039] According to a preferred embodiment of the present invention, the equivalent diameter of the serpentine reaction tube is 0.8 - 5 mm.

[0040] According to a preferred embodiment of the present invention, the equivalent diameter of the discharge main pipe is 2 - 10 mm.

[0041] According to a preferred embodiment of the present invention, the equivalent diameter of the radial feed pipe is 0.5 - 3 mm.

[0042] According to a preferred embodiment of the present invention, the reaction unit further includes: a heating unit, which is arranged to wrap the reaction unit and is used to provide heat for the reaction unit.

[0043] According to a preferred embodiment of the present invention, the reaction unit further includes: a heat insulation unit, which is arranged closely to the heating unit and is used to prevent heat dissipation in the device.

[0044] As Figure 1 shown, the present invention provides a device diagram and a process flow diagram of a preferred embodiment.

[0045] The device includes:

[0046] A microchannel reactor 4 (including at least two series-connected microchannel reaction devices), and a first raw material tank 1 connected to the olefin raw material feed main pipe of the microchannel reactor 4, with a first metering pump 6 arranged on the connecting pipeline; a second raw material tank 2 connected to the radial aqueous phase feed pipeline of the microchannel reactor 4, with a second metering pump 7 arranged on the connecting pipeline; a third raw material tank 3 connected to the output pipeline of the second metering pump 7, with a third metering pump 8 arranged on the connecting pipeline; and a first product collection tank 5 connected to the discharge main pipe of the microchannel reactor 4.

[0047] The reaction process includes: the first raw material (olefin raw material such as butene 11) is injected into the microchannel reactor 4 from the first raw material tank 1, the second raw material (auxiliary aqueous solution 12) is output from the second raw material tank 2, and after being combined with the third raw material (catalyst aqueous solution 13) output from the third raw material tank 3, it is injected into the microchannel reactor 4. The two raw materials collide and mix, and the first reaction product 15 is sent into the first product collection tank 5 for oil-water two-phase separation to obtain the first aqueous phase 17 and the first organic phase 16.

[0048] As Figure 2As described, it is a schematic diagram of the internal structure of a microchannel reactor according to a preferred embodiment of the present invention. The main feed inlet of the microchannel reactor is connected to a plurality of feed branches. The internal channel is a circular channel. The two feed branches form a certain angle along the liquid flow direction. The liquid inlet is distributed in an umbrella shape and is divided into two paths in total. Two vertical (radial) feed inlets are provided at the end of the liquid distribution area (the ends of the two feed branches). The reaction area is serpentine. The diameter of the axial inlet channel (main feed inlet) of the microchannel reactor is 1-8 mm, the diameter of the axial umbrella-shaped distribution channel (feed branch) is 0.5-4 mm, the diameter of the serpentine reaction channel is 0.8-5 mm, the diameter of the axial outlet channel (main discharge pipe) is 2-10 mm, and the diameter of the radial channel (radial feed pipe) is 0.5-3 mm. The short arc of the serpentine reaction area is the short arc intercepted at the diameter of a circle with a diameter of 1.6-10 mm. The number of short arcs is not less than 3, and they are tangent to each other in a peak-valley shape. A heating layer 9 is closely attached to the outside of the microchannel reactor, and a heat insulation layer 10 is closely attached to the heating layer. The short arc intercepted at the diameter. The number of short arcs is not less than 3, and they are tangent to each other in a peak-valley shape. A heating layer 9 is closely attached to the outside of the microchannel reactor, and a heat insulation layer 10 is closely attached to the heating layer.

[0049] The present invention will be described in detail below through examples. In the following examples, the contents of the raw material olefins and the corresponding product alcohols are obtained by gas chromatography analysis, and the corresponding conversion rates and selectivities are obtained by stoichiometry; unless otherwise specified, the raw materials are commercially available products.

[0050] Comparative Example 1

[0051] It is carried out in the device shown in Figure 1 and Figure 2 wherein, the main feed inlet of the microchannel reactor is connected to a plurality of feed branches. The internal channel is a circular channel. The two feed branches form a 90° angle along the liquid flow direction. The liquid inlet is distributed in an umbrella shape and is divided into two paths in total. Two vertical (radial) feed inlets are provided at the end of the liquid distribution area (the ends of the two feed branches). The reaction area is serpentine. The diameter of the axial inlet channel of the microchannel reactor is 5 mm, the diameter of the axial umbrella-shaped distribution channel is 2.5 mm, the diameter of the serpentine reaction channel is 4 mm, the diameter of the axial outlet channel is 7 mm, and the diameter of the radial channel is 2 mm. The short arc of the serpentine reaction area is the short arc intercepted at the diameter of a circle with a diameter of 8 mm. The number of short arcs is 6, and they are tangent to each other in a peak-valley shape. The short arc intercepted at the diameter. The number of short arcs is 6, and they are tangent to each other in a peak-valley shape.

[0052] The mixed C4 (the composition of the mixed C4 raw material is shown in Table 1) is fed into the axial channel in the microchannel reactor by a metering pump, and an aqueous solution containing 35 wt% tungstosilicic acid + 1 wt% silicic acid enters the radial channel in the microchannel reactor. The two streams collide and quickly enter the reaction zone for the first-stage hydration reaction. Subsequently, they converge at the outlet and enter the first collection tank for stratification. The upper layer is the butene organic phase, and the lower layer is the aqueous phase. The molar ratio of mixed C4 (calculated as butene, the same below) to water is 1:2.5, the hydration reaction temperature of the mixed C4 is 165 °C, and the pressure is 7 MPa. The reaction results are shown in Table 2.

[0053] Example 1

[0054] The operating process of this example is the same as that of Comparative Example 1, except that 2 wt% Tween 60 (HLB value is 14.9) is added to the aqueous phase. The reaction results are shown in Table 2.

[0055] Example 2

[0056] The operating process of this example is the same as that of Example 1, except that tungstosilicic acid + silicic acid is replaced by phosphomolybdic acid + phosphoric acid. The reaction results are shown in Table 2.

[0057] Example 3

[0058] The operating process of this example is the same as that of Example 1, except that the mixed C4 is fed into the axial channel in the microchannel reactor by a metering pump, and an aqueous solution containing 36 wt% phosphomolybdic acid + 0.8 wt% phosphoric acid + 3 wt% Tween 80 (HLB value is 15) enters the radial channel in the microchannel reactor. The two streams collide and quickly enter the reaction zone for the hydration reaction. Subsequently, they converge at the outlet and enter the first collection tank for stratification. The upper layer is the butene organic phase, and the lower layer is the aqueous phase. The molar ratio of mixed C4 to water is 1:4, the hydration reaction temperature is 170 °C, and the pressure is 7 MPa. The organic phase then enters the secondary microchannel reactor for the secondary hydration reaction, and the molar ratio of mixed C4 to water is 1:3.9, that is, two-stage hydration reaction is carried out. The reaction results are shown in Table 2.

[0059] Example 4

[0060] The operating process of this example is the same as that of Example 1, except that the aqueous solution containing 35 wt% tungstosilicic acid + 1 wt% silicic acid + 2 wt% Tween 60 (HLB value is 14.9) is replaced by an aqueous solution containing 40 wt% phosphomolybdic acid + 2 wt% alkylphenol polyoxyethylene ether-10 (HLB value is 14.5) + 0.8 wt% silicic acid, the hydration reaction temperature is 180 °C, the pressure is 7 MPa, the number of hydration reaction stages is 3, the water-to-olefin ratio in the first-stage reaction is 4:1, the water-to-olefin ratio in the second-stage reaction is 3.9:1, and the water-to-olefin ratio in the third-stage reaction is 3.8:1. The reaction results are shown in Table 2.

[0061] Example 5

[0062] The operating process of this example is the same as that of Example 1, except that the hydration reaction temperature is 185 °C, the pressure is 9 MPa, the hydration reaction stage is 4, the water-olefin ratio in the first-stage reaction is 2.5:1, the water-olefin ratio in the second-stage reaction is 2.4:1, the water-olefin ratio in the third-stage reaction is 2.3:1, and the water-olefin ratio in the fourth-stage reaction is 2.1:1. The reaction results are shown in Table 2.

[0063] Example 6

[0064] The operating process of this example is the same as that of Example 3, except that 0.5 wt% polyethylene glycol 400 is further added to the aqueous phase. The reaction results are shown in Table 2.

[0065] Example 7

[0066] The operating process of this example is the same as that of Example 3, except that phosphoric acid is not added to the aqueous phase. The reaction results are shown in Table 2.

[0067] Example 8

[0068] The operating process of this example is the same as that of Example 3, except that the raw material is cyclohexene and the reaction temperature is 150 °C. The reaction results are shown in Table 2.

[0069] Example 9

[0070] The operating process of this example is the same as that of Example 3, except that the emulsifier is Span 20 (HLB value is 8.6). The reaction results are shown in Table 2.

[0071] Comparative Example 2

[0072] The operating process of this comparative example is the same as that of Example 3, except that the Tween 80 additive is not added. The reaction results are shown in Table 2.

[0073] Comparative Example 3

[0074] The operating process of this comparative example is the same as that of Example 3, except that the reactor is a conventional microchannel reactor, the first feed main pipe is directly connected to the reaction zone, and the reaction zone is linear. The reaction results are shown in Table 2.

[0075] Comparative Example 4

[0076] The operating process of this comparative example is the same as that of Example 1, except that 2 wt% Tween 60 is replaced by 2 wt% polyethylene glycol 400. The reaction results are shown in Table 2.

[0077] Table 1 Composition of Mixed C4 Raw Materials

[0078] Chemical name Content (mol%) n-Butane 7.61 trans-2-Butene 61.55 cis-2-Butene 30.68 Others 0.16

[0079] Table 2 Results of Olefin Hydration Reaction

[0080] Butene molar conversion rate (%) Alcohol selectivity (%) Example 1 32.41 99.32 Example 2 30.84 99.56 Example 3 65.92 99.27 Example 4 84.41 99.14 Example 5 93.33 98.73 Example 6 68.42 99.18 Example 7 63.48 99.28 Example 8 Cyclohexene conversion rate 26.74 98.47 Example 9 50.54 98.62 Comparative example 1 20.43 97.55 Comparative example 2 41.98 98.17 Comparative example 3 32.63 99.19 Comparative example 4 22.55 98.79

[0081] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should equally be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for olefin hydration, characterized in that, the method comprises: carrying out a hydration reaction between an olefin raw material and water in the presence of a first auxiliary agent, optionally a second auxiliary agent and a catalyst; the first auxiliary agent contains an emulsifier.

2. The method according to claim 1, wherein, the HLB value of the emulsifier is 10 - 20; preferably, the emulsifier is selected from at least one of Tween, nonylphenol polyoxyethylene ether compounds, alkylphenol polyoxyethylene ether compounds, preferably at least one of Tween 20, Tween 40, Tween 60, Tween 80, nonylphenol polyoxyethylene ether - 10, nonylphenol polyoxyethylene ether - 15, alkylphenol polyoxyethylene ether - 10.

3. The method according to claim 1 or 2, wherein, the first auxiliary agent further includes a water - soluble diol reagent with a carbon number ≥ 4; preferably, the water - soluble diol reagent with a carbon number ≥ 4 is selected from at least one of diethylene glycol, triethylene glycol, polyethylene glycol 400, polyethylene glycol 600; more preferably, the mass ratio of the emulsifier to the water - soluble diol reagent with a carbon number ≥ 4 in the first auxiliary agent is 50 - 90:50 - 10.

4. The method according to any one of claims 1 - 3, wherein, the second auxiliary agent is an inorganic acid, preferably the inorganic acid is selected from phosphoric acid and / or silicic acid.

5. The method according to any one of claims 1 - 4, wherein, the catalyst includes a heteropolyacid catalyst, preferably the heteropolyacid catalyst is selected from phosphomolybdic acid and / or tungstosilicic acid.

6. The method according to any one of claims 1 - 5, wherein, the olefin raw material contains C4 - C6 olefins, preferably a raw material containing butene.

7. The method according to any one of claims 1 - 6, wherein, the method comprises: contacting the olefin raw material with an aqueous phase containing a first auxiliary agent, a second auxiliary agent and a catalyst to carry out a hydration reaction; preferably, the content of the first auxiliary agent in the aqueous phase is 0.3 - 8 wt%, the content of the second auxiliary agent is 0.5 - 1.5 wt%, and the content of the catalyst is 15 - 40 wt%.

8. The method according to any one of claims 1 - 7, wherein, the conditions of the hydration reaction include: temperature 150 - 200 °C; and / or pressure 5 - 15 MPa; and / or water - to - olefin molar ratio 2 - 8.

9. The method according to any one of claims 1 - 8, wherein, the method comprises re - carrying out the hydration reaction on the organic phase stream obtained from the hydration reaction, repeating 1 - 4 times, preferably, the water - to - olefin molar ratio of the latter hydration reaction is 0.1 - 0.2 lower than that of the previous hydration reaction.

10. The method according to any one of claims 1 - 9, wherein, the method is carried out in a device, and the device includes: an olefin raw material feeding system, an aqueous phase feeding system, and a reaction separation system; the reaction separation system includes alternately arranged micro - channel reaction units and oil - water two - phase separation units; The microchannel reaction unit includes at least two, preferably 2 - 4, microchannel reaction structures arranged in series and / or parallel in sequence for carrying out the mixing and hydration reaction of an olefin raw material and an aqueous phase; the reaction structure includes an olefin raw material feed main pipe and a product discharge main pipe, and a serpentine reaction pipe located between the olefin raw material feed main pipe and the product discharge main pipe. There are at least two serpentine reaction pipes, and both ends of each serpentine reaction pipe are respectively formed into a feed end and a discharge end. Among them, the discharge end of each serpentine reaction pipe is communicated with the product discharge main pipe, and the feed end of each serpentine reaction pipe extends to the olefin raw material feed main pipe to form a feed branch pipe. Among them, the included angle between the axes of the feed branch pipes of any serpentine reaction pipe is not less than 20°, and a radial aqueous phase feed pipe is communicated and arranged on any feed branch pipe; The olefin raw material feed system is communicated with the first microchannel reaction unit in the material flow direction; The aqueous phase feed system is communicated with each microchannel reaction unit.

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