System of producing propylene oxide (PO)

Abstract

To provide a system capable of providing PO under an appropriate condition in a production method including purifying, dehydrating, and hydrogenating bio-derived crude glycerin to obtain propylene glycol (PG), and thereafter dehydrating to derive propylene oxide (PO).SOLUTION: A system of producing PO from glycerin includes: a storage vessel system including a glycerin storage vessel; and a reaction vessel system including a reaction vessel for reduction and dehydration of a cycling plug flow, wherein PO is continuously supplied from a dehydration reaction vessel, a glycerin liquid is continuously supplied to the glycerin storage vessel, the glycerin liquid of the glycerin storage vessel and hydrogen are supplied to the upstream of a reduction reaction vessel and a mixed liquid of the glycerin liquid and the PG liquid is supplied to the glycerin storage vessel from a down stream of the reduction reaction vessel, and the glycerin storage vessel is a PG glycerin storage vessel from which a PG gas is supplied to an upstream of the dehydration reaction vessel.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a propylene oxide (PO) production system. [Background technology]

[0002] Propene oxide (PO) is a raw material for various chemical products, such as various urethanes, unsaturated polyesters, and modified silicone sealants (such as Kaneka MS Polymer (registered trademark)). It is mainly produced from naphtha derived from crude oil.

[0003] If such PO can be derived from biomass-derived raw materials (for example, waste oil or waste glycerin, a by-product of producing biodiesel fuel, which is expected to increase in the future), and bio-derived chemical products, such as MS polymers, can be provided as industrial products at reasonable prices and other conditions, it will contribute to carbon neutrality and resource circulation.

[0004] For example, Patent Document 1 discloses a glycol production method for producing glycol from glycerin, characterized in that a catalyst containing copper as an ingredient is used to carry out a reaction under atmospheric pressure or under pressure in the coexistence of hydrogen, and a 1-propanol production method that includes the production method as one step. The document discloses that BDF (Bio Diesel Fuel), which has attracted attention in recent years as a renewable energy source, is produced by transesterifying animal and vegetable oils, which are fats and oils, into methyl esters (FAME) using methanol and a catalyst, but that a large amount of glycerin is by-produced during this process. At present, no definitive means has been found for effectively utilizing this by-product glycerin, which poses a significant problem from the perspective of effective utilization of resources, and that a method for effectively utilizing the glycerin is desired. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication WO2010 / 016462 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, it is expected that bio-derived chemical products will be provided as industrial products under appropriate conditions such as price, and the present inventors have focused on the fact that, although glycerin, which is a by-product when producing biodiesel fuel from waste oil, is expected to increase in response to the trend toward biofuel in the future, by-product glycerin (crude glycerin) contains many impurities and is mainly reused as a soil conditioner, an additive for fertilizer, fuel, and other inexpensive products, and is not necessarily used effectively. If propylene oxide can be derived from this crude glycerin, it is thought that useful chemical products such as Kaneka MS Polymer can be provided as industrial products under appropriate conditions, and it will not only contribute to future carbon neutral measures such as bio-recycling of fossil fuels as raw materials and valuing waste, but also lead to maintaining the competitiveness of current businesses that use fossil fuels as raw materials from an ESG perspective in the future, such as Kaneka's MS business.

[0007] An object of the present invention is to provide a PO production system capable of providing propylene oxide (PO) under appropriate conditions in a production method that uses crude glycerin obtained by transesterifying waste oil to separate and recover biodiesel fuel and crude glycerin, specifically bio-derived crude glycerin, as a raw material, refines the crude glycerin using sulfuric acid or a sulfate, brings the refined glycerin into contact with a metal catalyst (e.g., copper-based) to react (dehydrate and hydrogenate (reduce)) to obtain propylene glycol (PG), and brings the obtained PG into contact with an alkali metal carbonate catalyst for dehydration to derive PO. [Means for solving the problem]

[0008] In view of the above-mentioned problems, the present inventors conducted various studies based on the hypothesis that it may be possible to provide PO under appropriate conditions by establishing a system in which reaction raw materials, intermediate products, and energy are reconsidered from a recycling perspective based on ESG considerations, and as a result, they have completed the present invention.

[0009] That is, the present invention is a propylene oxide (PO) production system for producing PO from glycerin, a storage tank system including a glycerin storage tank; a reactor system including a circulating plug flow reduction reactor and a circulating plug flow dehydration reactor; Including an input system and a recovery system, PO is continuously supplied from the circulating plug flow dehydration reactor, A glycerin liquid is continuously supplied to the glycerin storage tank, The glycerin liquid in the glycerin storage tank and hydrogen are supplied to the upstream of the circulating plug flow reduction reactor, A mixture of a glycerin liquid and a propylene glycol (PG) liquid is supplied to the glycerin storage tank from downstream of the circulating plug flow reduction reaction tank, The glycerin storage tank comprises: From that vessel, PG gas is fed upstream of the circulating plug flow dehydration reactor. Regarding a PO production system, which is a PG glycerin storage tank, such a PO production system can provide PO under appropriate conditions.

[0010] Furthermore, in the PO production system of the present invention, the raw materials contain bio-derived products, i.e., it is preferable that 10% by weight or more of the raw materials are bio-derived products. Although the raw materials may contain fossil fuel-derived products, at least the main raw materials are bio-derived products, i.e., it is more preferable that 50% by weight or more of the raw materials are bio-derived products, and even more preferable that 90% by weight or more of the raw materials are bio-derived products. It is particularly preferable that most of the raw materials, i.e., 99% by weight or more of the raw materials are bio-derived products. In other words, in the carbon-14 method or C-14 method described later, the carbon element contained in the PO of the present invention or a product derived therefrom has a 14C carbon content of at least 1.25×10 -13(-) or more is preferable, and 0.625×10 -12 (-) or more is more preferable, and 1.125×10 -12 More preferably, there is at least (-) -12 It is particularly preferred that (-) or more is present.

[0011] In addition, it is preferable that the PO production system produces PO from waste oil via the glycerin, and the storage tank system further includes a waste oil storage tank, a biofuel storage tank, and a methanol storage tank, the reactor system further comprising a continuously stirred transesterification reactor; In the continuous agitation transesterification reactor, The waste oil from the waste oil storage tank, and Methanol is discharged from the methanol storage tank. It is continuously supplied and The methanol in the methanol storage tank is preferably a PO-methanol solution obtained by continuously supplying PO from the circulating plug flow dehydration reactor, and PO can be provided under more appropriate conditions.

[0012] The reactor system further comprises a continuously stirred pH controlled reactor, The precipitate (lower layer) is continuously fed into the continuously stirred pH controlled reactor; It is preferable that the pH-adjusted intermediate layer component (middle layer) of the continuous stirring, pH-adjusted reaction tank is continuously supplied to the glycerin storage tank as the glycerin liquid.

[0013] The glycerin storage tank further comprises: a PG gas sub-storage tank for supplying the PG gas upstream of the circulating plug flow dehydration reactor; and The glycerin liquid is preferably supplied upstream of the circulating plug flow reduction reaction tank and includes a purified glycerin liquid sub-storage tank for maintaining the purified glycerin liquid at 50°C or higher and 200°C or lower, and more preferably includes an impurity-containing glycerin liquid sub-storage tank for discharging the impurity-containing glycerin liquid containing impurities to the outside. Effect of the Invention

[0014] The PO production system of the present invention can provide PO under appropriate conditions.

Brief Description of the Drawings

[0015] [Figure 1] It is a flowchart for explaining an embodiment of a propylene oxide (PO) production system 1 of the present invention. [Diagram 2] It is a photograph of a separating funnel in a state of being allowed to stand and separated after transesterification in each waste oil (waste oil A, waste oil B, waste oil C) in the <Glycerin production process element experiment> regarding the glycerin production process according to the present invention, where the lower layer is crude glycerin and the upper layer is crude biodiesel fuel. [Diagram 3] It is the weight concentration (%) of pure glycerin obtained by GC analysis at each stage of crude glycerin after transesterification, neutralized glycerin after neutralization, and purified glycerin after addition of inorganic salts in each waste oil (waste oil A, waste oil B, waste oil C) in the <Glycerin production process element experiment>. [Figure 4] It is a flowchart for explaining an embodiment of a glycerin production process according to the present invention. [Diagram 5] It is a photograph of an experimental apparatus in one embodiment of the <PG production sub-process element experiment> regarding the PG production sub-process included in the PO production process according to the present invention. [Figure 6] It is a photograph of an experimental apparatus in the <PG production sub-process element experiment> of this specification. [Figure 7] It is the molar yield (%) of the produced PG with respect to the input glycerin after the elapsed time (horizontal axis) after reaching a reaction temperature of 200 °C for each catalyst (Ni-based, copper oxide I, copper oxide II, copper powder) in the <PG production sub-process element experiment> of this specification (vertical axis). [Figure 8] It is a flowchart for explaining an embodiment of a PG production sub-process according to the present invention. [Figure 9] It is a photograph of an experimental apparatus in one embodiment of the <PG dehydration sub-process element experiment> regarding the PG dehydration sub-process included in the PO production process according to the present invention. [Figure 10]It is a cross-sectional schematic diagram for explaining a photograph of the experimental apparatus in FIG. 9. [Figure 11] It is the molar yield (%) (vertical axis) of the produced PO with respect to the input PG at each reaction temperature and each reaction time (horizontal axis) in the <PG dehydration sub-process element experiment> of this specification. [Figure 12] It is a flowchart for explaining one embodiment of the PG dehydration sub-process according to the present invention.

Mode for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described in detail while explaining each component according to the present invention.

[0017] (Propylene Oxide (PO) Production System 1) FIG. 1 is a flowchart for explaining one embodiment of the propylene oxide (PO) production system 1 of the present invention.

[0018] The propylene oxide (PO) production system 1 of the present invention is a system capable of implementing at least a process for producing PO from glycerin. As mechanisms or components, it includes a storage tank system for storing raw materials, intermediate products, and final products, a reaction tank system for causing a chemical reaction in at least a part of the supplied materials and supplying the obtained reaction products, a gas supply system for supplying at least hydrogen gas, a supply system 190 for inputting raw materials and energy into the system 1, and a recovery system 191 for recovering PO and the like from the system 1. Optionally, it includes a waste disposal system 193 for disposing of unnecessary liquids and gases outside the system.

[0019] The PO production system 1 of the present invention preferably includes, in addition to the PO production process for producing PO from the aforementioned glycerin, a glycerin production process for producing glycerin from waste oil. More preferably, the glycerin production process can produce biofuel as a by-product.

[0020] The PO production process includes a propylene glycol (PG) production sub-process of producing PG from glycerin, and a PG dehydration sub-process of producing PO from PG.

[0021] The storage tank system includes at least a glycerin storage tank 10 for storing glycerin, and preferably further includes a waste oil storage tank 16, a biofuel storage tank, and a methanol storage tank 18.

[0022] The reaction vessel system includes at least a circulating plug flow reduction reaction vessel 11 and a circulating plug flow dehydration reaction vessel 12, and further includes preferably a continuous stirring transesterification reaction vessel 14, and more preferably a continuous stirring pH adjustment reaction vessel 15.

[0023] (Waste oil tank 16) The waste oil storage tank 16 is a tank for storing and storing waste oil, and is capable of receiving various types of waste oil.

[0024] (Biofuel storage tank) The biofuel storage tank is a tank to which biofuel derived from the supernatant (upper layer) of the continuous stirring transesterification reactor 14 is continuously supplied, and crude biodiesel can be recovered and stored.

[0025] (Glycerin tank 10) The glycerin storage tank 10 is a tank to which a glycerin liquid derived from the sediment (lower layer) in the continuous stirring transesterification reaction tank 14 is continuously supplied, and is also a PG glycerin storage tank for supplying PG gas upstream of the circulating plug flow dehydration reaction tank 12, which is one of the features of the present invention. Preferably, the glycerin storage tank 10 is supplied with PG liquid derived from unreacted PG gas from the circulating plug flow dehydration reaction tank 12, which will be described later.

[0026] Such a glycerin storage tank 10 preferably includes at least a PG gas sub-storage tank 101 mainly responsible for supplying the above-mentioned PG gas upstream of the circulating plug flow dehydration reaction tank 12, and a purified glycerin liquid sub-storage tank 102 in which a purified glycerin liquid, which is glycerin with a reduced impurity content in the glycerin storage tank 10, is stored and which has an insulation mechanism for maintaining the purified glycerin liquid at 50°C or higher and 200°C or lower, and more preferably includes an impurity-containing glycerin liquid sub-storage tank 103 which mainly plays a role of continuously supplying glycerin liquid derived from the sediment (lower layer) in the above-mentioned continuous stirring transesterification reaction tank 14, and which is a tank capable of discharging impurity-containing glycerin liquid containing impurities to the outside.

[0027] (Methanol tank 18) The methanol storage tank 18 is a tank for storing methanol to which PO is continuously supplied from the circulating plug flow dehydration reaction tank 12. One of the features of the present invention is that the methanol storage tank 18 is a tank for storing such a PO-methanol solution. Specifically, it is preferable that the PO gas continuously supplied from the circulating plug flow dehydration reaction tank 12 is bubbled into the PO-methanol solution so that the PO gas can be collected in the solution.

[0028] (Continuously stirred transesterification reactor 14) The continuous stirring transesterification reaction tank 14 is a tank to which waste oil from a waste oil storage tank 16 and methanol from a methanol storage tank 18 are continuously supplied, and in which a transesterification reaction between the waste oil and methanol is carried out. As a result of the transesterification reaction, biofuel and glycerin are produced in this tank, and the liquid containing these raw materials and products is stirred to increase the reaction efficiency.

[0029] From the continuous stirring transesterification reaction tank 14, preferably the sediment in the lower tank of the tank is supplied as a crude glycerin liquid to the continuous stirring pH adjustment reaction tank 15 described below.

[0030] (Continuous stirring pH adjustment reactor 15) The continuous stirring pH adjustment reaction tank 15 is a tank to which the crude glycerin liquid is continuously supplied from the continuous stirring transesterification reaction tank 14, and is used as a reaction tank in which sulfuric acid, magnesium sulfate, etc. are added to improve the purity of glycerin. Furthermore, the purity of the glycerin liquid is improved by shifting the pH in the tank to the acid side, and specifically, a reaction occurs in which higher fatty acids are liberated from the intermediate layer and lower fatty acids become fatty acid salts, and a purified glycerin liquid is generated as a pH-adjusted intermediate layer component, preferably in the intermediate layer below the stirring part, and this liquid is continuously supplied to the glycerin storage tank 10 as the glycerin liquid according to the present invention. Also, higher fatty acids and lower fatty acids are generated in the upper tank above the stirring part, and as necessary, they are recovered from the upper layer or discarded via the disposal system 193 according to the present invention.

[0031] (Circulating plug flow reduction reactor 11) The circulating plug flow reduction reaction tank 11 is a reaction tank into which a glycerin liquid in a glycerin storage tank 10 and hydrogen gas from a gas supply system 13 according to the present invention are supplied upstream, and into which a mixed liquid of the glycerin liquid and propylene glycol (PG) liquid is supplied downstream to the glycerin storage tank 10. At least a portion of the glycerin liquid is reduced by the hydrogen gas in the presence of a copper-based catalyst such as CuO or Cu powder, and is also dehydrated to become PG liquid. The mixed liquid containing the PG liquid produced in this manner is supplied to the glycerin storage tank 10.

[0032] The circulating plug flow reduction reactor 11 must be kept at 290°C or less in order to efficiently react with the mixed liquid while maintaining the mixed liquid in a liquid state. It is preferable that the unreacted hydrogen gas can be recovered, i.e., the amount of hydrogen gas used can be significantly reduced by reusing the unreacted hydrogen gas. The amount of hydrogen gas to be transferred and supplied is preferably 11 or more equivalents relative to the amount of continuous glycerin supply in the glycerin liquid for an equimolar reaction, for example, to improve three-phase interface contact with the catalyst by forming a slug flow, turbulence, or microbubbles, and at least 10 equivalents of the hydrogen gas can be recovered and reused as unreacted hydrogen gas. The "circulation" in the "circulating plug flow reduction reactor" expresses the situation in which "unreacted hydrogen can be recovered and reused."

[0033] (Circulating plug flow dehydration reactor 12) PG gas is supplied to the upstream of the circulating plug flow dehydration reaction tank 12 from the PG glycerin storage tank 10 according to the present invention, and PO gas is continuously supplied to the methanol storage tank 18 by a dehydration reaction in the presence of a catalyst such as an alkali metal carbonate. Preferably, unreacted PG gas is cooled and liquefied by a heat exchanger disposed downstream of the circulating plug flow dehydration reaction tank 12, and then heated to 188°C or higher in the PG gas sub-storage tank 101 and supplied again upstream of the circulating plug flow dehydration reaction tank 12.

[0034] This type of circulating plug flow dehydration reactor 12 must be kept at 188°C or higher in order to maintain PG in a gaseous state while efficiently reacting it with the catalyst, and in order to reduce unreacted PG gas and increase the amount of PO gas produced, it must be possible to recover unreacted PG gas from the entire system; in other words, it is preferable that the amount of raw material used can be significantly reduced by reusing the unreacted PG gas, and the word "circulating" in "circulating plug flow dehydration reactor" expresses the situation in which "unreacted PG gas can be recovered and reused."

[0035] (Confirming products made from non-fossil fuel-derived raw materials by measuring isotopic carbon content) In the PO production system of the present invention, the raw materials, PO, or PO-derived products preferably contain biological origins. Although they may contain fossil fuel-derived products, it is more preferable that at least the main raw materials are biological origins. Whether or not the PO is derived from such biological origin raw materials, i.e., whether or not the PO is produced by the production method of the present invention, can be confirmed by using a method for dating an object containing organic matter, making use of the properties of 14C, a radioactive isotope of carbon, generally referred to as the carbon-14 method or C14 method.

[0036] The carbon-14 method, or C14 method, is a method for estimating the time when environmental carbon exchange ceases based on the age decay of the 14C carbon that exists at a certain concentration due to the action of cosmic rays on 14N nitrogen, which is induced by the uptake equilibrium of 14C carbon via photosynthesis in the living organisms and the cessation of environmental carbon exchange. Since the half-life of 14C carbon is approximately 5730 years, fossil fuels and their derived materials that are produced over a very long period of time contain almost no 14C carbon. On the other hand, in biologically derived materials, the ratio of 14C carbon to 12C carbon is 1.25:10. 12 is contained in the total carbon.

[0037] The amount of 14C carbon can be measured by detecting the beta rays emitted during the decay of 14C carbon in the sample using a beta ray counter, or by directly counting and converting the total amount of 14C carbon using accelerator mass spectrometry (AMS). EXAMPLES

[0038] The present invention will be explained below with reference to relevant elemental experiments.

[0039] <Glycerin manufacturing process element experiment> Waste oil was mixed with methanol and alkali (KOH) in a weight ratio of 300:40:1 to carry out an ester exchange reaction. That is, after mixing and stirring these in a separable flask at 65°C, this was poured into a separatory funnel and allowed to stand for separation. The lower layer was collected as crude glycerin and analyzed by GC, and the upper layer was also collected separately.

[0040] FIG. 2 is a photograph of the separatory funnel immediately before recovery, i.e., a photograph of the separatory funnel in a state where the waste oils (waste oil A, waste oil B, waste oil C) were left to stand and separated after transesterification in <Glycerin Production Process Element Experiment> for the glycerin production process according to the present invention, in which the lower layer is crude glycerin and the upper layer is crude biodiesel fuel.

[0041] Next, the crude biodiesel fuel was added to the recovered crude biodiesel fuel in a weight ratio of 250:30:0.75 crude biodiesel fuel:methanol:alkali (KOH), which was stirred and mixed, and then the mixture was poured into a separatory funnel and allowed to stand for separation. The crude glycerin in the lower layer was recovered and analyzed by GC.

[0042] Next, concentrated sulfuric acid was added to the recovered crude glycerin, which was then stirred and neutralized. The water and methanol were then separated and removed using an evaporator, and the mixture was then separated into three layers by centrifugation. The middle layer was recovered as neutralized glycerin and analyzed by GC.

[0043] Finally, magnesium sulfate was added as an inorganic salt to the liquid in the intermediate layer, and the mixture was stirred at 90°C to separate the higher fatty acids as an upper layer. The remaining layer was further centrifuged, and the intermediate layer was recovered as purified glycerin after the addition of inorganic salts, and analyzed by GC.

[0044] Figure 3 shows the weight concentration (%) of glycerin obtained by GC analysis at each stage of the waste oils (Waste Oil A, Waste Oil B, Waste Oil C) in the <Glycerin Manufacturing Process Element Experiment>: crude glycerin after transesterification, neutralized glycerin after neutralization, and refined glycerin after addition of inorganic salts.

[0045] As shown in FIG. 3, glycerin with a purity of 90% by weight or more was obtained from three types of waste oil, waste oil A, waste oil B, and waste oil C, and palm oil in a separate experiment. By establishing a system according to the present invention, it is possible to obtain glycerin with a higher purity. Specifically, it is possible to obtain a higher purity by combining a method such as continuous supply and addition of inorganic salts while stirring, or application of ion exchange resin to a reaction tank and adsorption separation.

[0046] In addition, while the waste oil storage tank 16 according to the present invention is used as a mixing storage tank for injecting a plurality of types of waste oils including various waste oils procurable from the outside, such as waste cooking oil with little free fatty acid, etc., based on the results of extraction analysis and the calculation of the ratio of the types of waste oils to be injected, by making it possible to change the operating conditions of the entire system, the productivity of the entire system can be improved.

[0047] FIG. 4 is a flowchart for explaining an embodiment of the glycerin production process according to the present invention. In the continuous stirring transesterification reaction tank 14 according to the present invention, waste oil is continuously supplied from the waste oil storage tank 16, and a methanol solution of KOH obtained in a dissolution tank for dissolving KOH in methanol is also continuously supplied. The continuous stirring transesterification reaction tank 14 is directly connected in two pairs with a pair of tanks consisting of a stirring tank and a settling tank in sequence. In the continuous stirring pH adjustment reaction tank 15 according to the present invention, crude glycerin is continuously supplied from the continuous stirring transesterification reaction tank 14, and concentrated sulfuric acid is also supplied. The continuous stirring pH adjustment reaction tank 15 supplies purified glycerin.

[0048] <PG production sub-process element experiment> FIG. 5 is a photograph of an experimental apparatus in an embodiment of <PG production sub-process element experiment> for the PG production sub-process included in the PO production process according to the present invention, and is a photograph of a simple experimental apparatus for producing PG from glycerin.

[0049] FIG. 6 is a photograph of an experimental apparatus in another embodiment of <PG production sub-process element experiment> for the PG production sub-process included in the PO production process according to the present invention. Specifically, it is an experimental apparatus (high-pressure microreactor MMJ-100 manufactured by OMR Labtec Co., Ltd.) used for synthesizing PG from glycerin.

[0050] As the PG production sub-process element experiment, first, a mixture of glycerin and a catalyst (using Ni-based, copper(I) oxide, copper(II) oxide, or copper powder alone respectively) was put into the heat-resistant container of the experimental apparatus in FIG. 6, then covered, and the inside of the heat-resistant container was evacuated with a pump to a vacuum.

[0051] Next, hydrogen gas was allowed to flow from the gas pack into the heat-resistant container through a nozzle, and while stirring the mixture, the interior of the heat-resistant container was heated by heating the oil in the oil bath disposed therein, thereby heating the mixture to 180°C or 200°C. In this state, after 20 minutes, 60 minutes, 120 minutes, etc., the reaction mixture was analyzed by GC to confirm the reaction status.

[0052] Figure 7 shows the molar yield (%) of the produced PG with respect to the hydrogen input after the elapsed time (horizontal axis) after reaching a reaction temperature of 200°C for each catalyst (Ni-based, copper oxide I, copper oxide II, copper powder) in the <PG production sub-process element experiment>.

[0053] As shown in Figure 7, within the experimental range, the conversion rate was the highest after 120 minutes using the Ni-based catalyst, and the yield was 65%. The Ni-based catalyst used here is specifically the flake nickel catalyst SO750 manufactured by Sakai Chemical Industry Co., Ltd. with a high Ni content.

[0054] As such PG production catalysts, there are also other catalysts such as the alumina-supported copper oxide II-based catalyst, CuO / Al 2 O 3 catalyst, etc., which have been reported to have a PG conversion rate of 90% and a glycerin reaction rate of 100%, and can be suitably used in the system of the present invention, achieving an improvement in conversion rate and a shortening of the reaction time. Also, by using Cu nanoparticles as the copper powder-based catalyst, it is considered possible to produce PG with high selectivity and suppress the generation of by-products. In some cases, it is preferable to add such a catalyst as a co-catalyst when using the above-mentioned Ni-based catalyst or copper oxide II-based catalyst as the main catalyst.

[0055] By the way, in the case reported for the aforementioned CuO / Al 2 O 3 catalyst, hydrogen gas in an amount 40 to 160 times the stoichiometric ratio in the case of an equimolar reaction was allowed to flow in and ventilated, and as a result, it flowed out. It is possible to improve the contact efficiency at the three-phase interface of the raw material glycerin, hydrogen gas, and the catalyst, that is, by accelerating the hydrogenation reaction, the amount of hydrogen gas used can be suppressed, which is one of the features of the present invention.

[0056] FIG. 8 is a flowchart for explaining an embodiment of the PG production sub-process according to the present invention. In the circulating plug flow reduction reactor 11 according to the present invention, purified glycerin heated and having its viscosity reduced therein is continuously supplied from the glycerin storage tank 10, and hydrogen gas is also continuously supplied. While flowing in a SLUG flow, a turbulent flow, or a state in which hydrogen is micro-bubbled through a column filled with a catalyst which is a reaction field of the circulating plug flow reduction reactor 11, by efficiently forming the three-phase interface, from the downstream, the generated PG is supplied to the glycerin storage tank 10 together with unreacted glycerin, cooled therein, and supplied as a liquid. Further, from the glycerin storage tank 10, the generated PG gas obtained by vacuum distillation therein is supplied to the circulating plug flow dehydration reactor 12, and the unreacted glycerin liquid is circulated and supplied to the circulating plug flow reduction reactor 11 again. Further, in the circulating plug flow reduction reactor 11, the hydrogen gas flowing out from its downstream is circulated and supplied to its upstream.

[0057] <PG dehydration sub-process element experiment> FIG. 9 is a photograph of an experimental apparatus in an embodiment of <PG dehydration sub-process element experiment> for the PG dehydration sub-process included in the PO production process according to the present invention. The left photograph is the external appearance of the entire apparatus, and the right photograph is a mesh bag (inside the small circle) filled with a catalyst and tied to a sheath pipe, which is arranged in the large ellipse part of the left photograph.

[0058] FIG. 10 is a schematic cross-sectional view for explaining the photograph of the experimental apparatus of FIG. 9. Inside the internal reaction tank that can be heated from the outside by a heater included in the external appearance on the left side of FIG. 9, the aforementioned mesh bag is arranged together with a thermometer further inside, and the internal reaction tank is provided with an inflow pipe and an outflow pipe. The tip of the outflow pipe protrudes into a methanol liquid reservoir. In the PG dehydration sub-process element experiment, as shown in FIGS. 9 and 10, first, 15 g of potassium hydrogen carbonate (KHCO 3 15 g) is filled into a SUS mesh bag, and this is tied with a wire to a pipe passing through a flange lid which is a sheath pipe part of a high-temperature reactor (right figure) which is an internal reaction tank.

[0059] Next, about 1.5 g (0.02 mol) of PG was charged into the internal reaction tank, the flange lid was closed, and all the pipes related to the inflow and outflow communicating with the inside were blocked by stop valves to seal the internal reaction tank. After evacuating to expel the internal air, nitrogen (N 2 ) was introduced from the inlet pipe until the normal pressure was reached.

[0060] Thereafter, it was heated with a heater until the thermometer reached 250 °C, 300 °C, or 350 °C, and reacted by maintaining the state for 10 minutes, 30 minutes, or 60 minutes.

[0061] Finally, after the heater heating was completed and cooled until the thermometer reached about 60 °C, the internal gas of the internal reaction tank was expelled by introducing nitrogen from the inlet pipe, bubbled into methanol (MeOH), and the reaction product dissolved in methanol was recovered as a methanol solution. At the same time, nitrogen gas insoluble in methanol was released into the atmosphere, and the methanol solution thus obtained was analyzed by GC.

[0062] Figure 11 shows the molar yield (%) (vertical axis) of the produced PO with respect to the charged PG at each reaction temperature (250 °C, 300 °C, 350 °C) and each reaction time (horizontal axis: 10 minutes, 30 minutes, or 60 minutes) in the <PG dehydration sub-process element experiment>.

[0063] The highest yield in Figure 11 is about 25%, and a high yield of 30% of the PO yield has also been reported. By using the system of the present invention, it is considered that PO can be produced with a higher yield. However, it is necessary to determine the operating conditions (temperature, residence time, etc.) of the system in consideration of the balance of the entire system. Needless to say, the influence of by-products other than PO on the productivity of the system is also an important factor in the above determination. Such by-products include propionaldehyde, acetol, allyl alcohol, etc. For improving the PO selectivity, other solid basic catalysts, for example, preferably K 2 CO 3 、K 2By adding a co-catalyst such as O / CaO composite catalyst, other synthesis routes can also be applied to the PG dehydration sub-step of the system of the present invention.

[0064] FIG. 12 is a flow diagram illustrating one embodiment of the PG dehydration sub-step according to the present invention. PG gas heated and vaporized in glycerin storage tank 10 is continuously supplied to circulating plug flow dehydration reaction tank 12 according to the present invention, where it reacts while flowing through a column packed with a catalyst, which serves as the reaction field, and the PO produced is supplied downstream. This PO is stored in methanol storage tank 18, which stores a PO-methanol solution according to the present invention. In FIG. 12, the PO is recovered as PO gas from recovery system 191 in a distillation column included in methanol storage tank 18, and circulating plug flow dehydration reaction tank 12 is configured to include a cooling, stirring and distillation column downstream of the column, which supplies the produced PO downstream as a gas and recovers unreacted PG as a liquid.

Claims

1. A propylene oxide (PO) production system for producing PO from glycerin, comprising: a storage tank system including a glycerin storage tank; a reactor system including a circulating plug flow reduction reactor and a circulating plug flow dehydration reactor; Including an input system and a recovery system, PO is continuously supplied from the circulating plug flow dehydration reactor, and A glycerin liquid is continuously supplied to the glycerin storage tank, The glycerin liquid in the glycerin storage tank and hydrogen are supplied to the upstream of the circulating plug flow reduction reactor, A mixture of a glycerin liquid and a propylene glycol (PG) liquid is supplied to the glycerin storage tank from downstream of the circulating plug flow reduction reaction tank, From that vessel, PG gas is fed upstream of the circulating plug flow dehydration reactor. PG glycerin storage tank, PO manufacturing system.

2. 2. The PO manufacturing system according to claim 1, Regarding the PO, the carbon element in the carbon-14 method is 1.25×10 －１３ (-) PO manufacturing system that exists.

3. 3. The PO production system according to claim 1 or 2, which produces PO from waste oil via the glycerin, The storage tank system further includes a waste oil storage tank, a biofuel storage tank, and a methanol storage tank; and the reactor system further comprising a continuously stirred transesterification reactor; In the continuous agitation transesterification reactor, The waste oil from the waste oil storage tank, and Methanol is discharged from the methanol storage tank. It is continuously supplied and the methanol in the methanol storage tank is a PO-methanol solution obtained by continuously supplying PO from the circulating plug flow dehydration reactor.

4. the reactor system further comprising a continuously stirred, pH controlled reactor; The precipitate (lower layer) is continuously fed into the continuously stirred pH controlled reactor; The PO production system according to claim 3 , wherein a pH-adjusted intermediate layer component (middle layer) of the continuous stirring pH adjustment reaction tank is continuously supplied to the glycerin storage tank as the glycerin liquid.

5. The glycerin storage tank is a PG gas sub-storage tank for supplying the PG gas upstream of the circulating plug flow dehydration reactor; and a purified glycerin liquid sub-storage tank for maintaining the purified glycerin liquid supplied upstream of the circulating plug flow reduction reaction tank at a temperature of 50° C. or higher and 200° C. or lower, more preferably an impurity-containing glycerin liquid sub-storage tank for discharging the impurity-containing glycerin liquid containing impurities to the outside. The PO manufacturing system of claim 4 .

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