JP5736569B2 - Production method of fatty acid methyl ester using slag as catalyst - Google Patents

Description

  The present invention relates to a method for producing fatty acid methyl ester of biodiesel fuel by transesterifying oil (triglyceride) with methanol using slag discharged from a steel mill as a catalyst.

  In the Japanese steel industry, about 38 million tons of slag is discharged as a by-product of the iron making process annually. This slag is mainly classified into blast furnace (BF) slag, converter (LD) slag, and electric furnace (EAF) slag according to the manufacturing process, and the annual emissions are about 25 million tons, about 9.5 million tons, and about 3.5 million. (2006, Steel Slag Association, Steel Slag Statistics Annual Report).

  The blast furnace slag is further divided into slowly cooled slag and granulated slag according to the cooling method. Slow cooling slag is crystalline rock-like slag obtained by pouring discharged blast furnace slag into a cooling yard and cooling it by natural cooling and moderate watering. This slow cooling treatment is also used for both slags in converters and electric furnaces. Since the granulated slag is obtained by injecting pressurized water into the discharged blast furnace slag and simultaneously putting it into the water flow and rapidly cooling it, it becomes a vitreous (amorphous) granular slag. Blast furnace slag is discharged in the iron making process, and about 290 kg is produced per ton of pig iron.

  Converter slag and electric furnace slag are discharged in the steelmaking process, and about 121 kg and about 123 kg are produced per ton of crude steel, respectively. Currently, most of these steel slags are recycled for various purposes, taking advantage of their characteristics. As an example, blast furnace slag has components similar to natural rocks and is used as a concrete aggregate to show non-alkaline aggregate reaction, and granulated slag has strong latent hydraulic properties, so Used as a raw material. Since converters and electric furnace slag are hard and have excellent wear resistance, they are used in aggregates for asphalt concrete and are used as earthwork materials and ground improvement materials because of their high internal friction. Furthermore, since these slags commonly contain fertilizer components such as CaO and SiO2, they are also used for fertilizers and soil improvement materials.

  In this way, despite the development of various applications, steel slag is always in excessive supply, and further development of applications is expected in the future.

  In recent years, global warming due to an increase in greenhouse gas emissions is feared. For this reason, the production amount of biomass fuel, which emits less greenhouse gases than fossil fuels, is increasing from the carbon neutral point of view.

  Biodiesel fuels mainly composed of fatty acid methyl esters are produced around the world as an alternative to light oil, a fossil fuel, and the production volume is increasing year by year. In Germany and Austria, rapeseed oil is used as a raw material, and potassium hydroxide and sodium hydroxide are used as catalysts to produce fatty acid methyl esters by transesterification. In the United States, soybean oil is used as a raw material, and potassium hydroxide and sodium hydroxide are used as catalysts to produce fatty acid methyl esters by transesterification.

  However, potassium hydroxide and sodium hydroxide as catalysts for producing fatty acid methyl esters are dangerous substances for humans and have a problem in that they need to be handled with care.

  In addition, potassium hydroxide or sodium hydroxide reacts with free fatty acids contained in fats and oils during transesterification of fats and oils with methanol to produce surface active substances such as fatty acid potassium or fatty acid sodium and water. Also, since the fatty acid itself produces fatty acid potassium or fatty acid sodium and suppresses fatty acid methyl ester production, there is a problem of lowering the yield.

  Therefore, without using an alkali catalyst such as potassium hydroxide or sodium hydroxide, all fats and oils are decomposed into free fatty acids and then methyl esterified under subcritical reaction conditions to produce fatty acid methyl esters (Patent Document 1). Has been developed to avoid the dangers associated with handling the catalyst to humans and to reduce yields. However, since a subcritical reactor needs to withstand high temperature and pressure, the reactor is expensive. Therefore, since the equipment cost of an apparatus is high, there exists a problem that the production cost of fatty acid methyl ester becomes high.

  Moreover, even if it uses a catalyst, as a method of producing | generating the fatty acid methyl ester which can avoid the danger that a catalyst handles a human, and a yield fall, the production | generation method of the fatty acid methyl ester using an ion exchange resin as a catalyst (patent document 2) A method for producing a fatty acid methyl ester (Patent Document 3) used as a catalyst containing a composite metal oxide having a perovskite structure has been developed, but the production cost of the catalyst is high and the production cost of the fatty acid methyl ester is high. There is a problem.

JP 2007-9017 A JP 2007-14871 A JP 2002-294277 A

  In order to produce fatty acid methyl esters by transesterification of fats and oils with methanol, it is necessary to set optimum conditions for each reaction by using an acidic catalyst or a basic catalyst. However, in steel slag, the acidic catalyst component SiO2 · Al2O3 and the basic catalyst component CaO coexist, and a method to produce fatty acid methyl esters by transesterification of fats and oils with methanol in the presence of catalysts with different properties is provided Was not. Therefore, the present invention is to solve the problem of human handling of the catalyst in the production of fatty acid methyl ester, the reduction in yield due to the production of surface active components, and the high cost of the catalyst. In addition, the present invention provides a new application of steel slag in an excessive supply state.

The present invention provides a method for producing fatty acid methyl ester as biodiesel fuel by transesterifying fats and oils with methanol using blast furnace slag and steelmaking slag discharged from steelworks as catalysts. In addition, the present invention provides a method for increasing the activity of the catalyst slag and increasing the reaction efficiency of the method for producing fatty acid methyl ester by performing high-temperature treatment in an inert gas or dry cooling without using water.

  The slag having a basicity of 1 or more discharged at the steel works as a catalyst for transesterification of fats and oils and produces fatty acid methyl esters.

  Steel slag as a catalyst is much less expensive than potassium hydroxide, sodium hydroxide, ion exchange resins, and the like. Therefore, by using slag as a catalyst, the catalyst cost of producing fatty acid methyl ester as biodiesel fuel can be reduced, and as a result, the production cost of fatty acid methyl ester as biodiesel fuel can be reduced, resulting in excessive supply. There is also an effect that can provide the use of steel slag.

  The slag used as the catalyst preferably has a basicity (calcium oxide / silicon oxide ratio) of 3 or more, but even a slag having a basicity of about 1 such as a blast furnace slag is contained in the inert gas shown in claim 2. Fatty acid methyl ester can be produced to some extent by increasing the activity of the catalyst slag and increasing the reaction efficiency of the fatty acid methyl ester production method by high-temperature treatment or dry cooling without using water (FIG. 1, BF). slag1: granulated slag, BF slag2: dry cooling slag).

  Even a steelmaking slag having a basicity of around 3 (LD slag) does not show a catalytic effect without the heat treatment according to claim 2 (FIG. 1 LD slag 1). However, when heat treatment is performed at about 1000 ° C., a yield of 56% is obtained with a methyl transesterification reaction time of 6 hours (LD slag 2). Furthermore, the result of having sampled the methyl transesterification reaction time every 1 hour to 9 hours using slag (LD slag 3) heat-processed in inert gas (Ar) was shown in FIG. The production rate is 82% in 9 hours. In addition, when a relatively new steel slag (LD slag 4) lump is pulverized and heat-treated in air, the production rate is 92% even when the methyl transesterification reaction time is 6 hours, so the slag storage method is important. .

  The oil or fat is preferably vegetable oil or animal oil having a low free fatty acid content. However, even if a free fatty acid is contained, it is possible to produce a fatty acid methyl ester by increasing the amount of slag added as a catalyst to advance the transesterification reaction with oil and methanol.

  For the transesterification of fats and oils with methanol, the reaction temperature is optimally 60 ° C., but the higher the temperature is in the range of 40 to 100 ° C., the longer the reaction time can be, and the fatty acid methyl ester can be produced.

  The amount of methanol to be added to the fat / oil is optimally 400 g / kg of fat / oil, but transesterification proceeds to produce a fatty acid methyl ester in the range of 200 g / kg of fat / oil to 400 g / kg of fat / oil.

  In the transesterification of oil and methanol, the reaction temperature is preferably 60 ° C., but in the range of 20 to 90 ° C., the amount of methanol added is 400 g / kg of oil or fat, and the reaction time is preferably 4 hours or more.

  The amount of catalyst slag is preferably 500 g / kg of oil or fat, but methyl ester can be produced in the range of 50 to 500 g / kg of fat. In this case, it is desirable to increase the reaction time and the temperature.

Production of Fatty Acid Methyl Ester Using Blast Furnace Slag as Catalyst BF slag 1 and BF slag 2 in FIG. 1 are obtained by dry-cooling blast furnace granulated slag and blast furnace slag , respectively. Table 1 shows the methyl ester exchange reaction conditions for 100 g of fats and oils when blast furnace slag is used. BF slag 2 is considered to have a form in which crystalline phases of Merwinite and Gehlenite are mixed by dry cooling , and these have a catalytic function of methyl ester formation .

Production of fatty acid methyl ester using steel slag (LD slag) as a catalyst LD slag 1 and LD slag 2 in FIG. 1 use steel slag without treatment.
Shows the methyl transesterification reaction conditions for 100 g of fat and oil. By firing steelmaking slag (LD slag 2), CaO in the slag was regenerated (considered to have been Ca (OH) 2 or CaCO3 because it was left in the atmosphere), and the methyl ester content was 6 hours. It increased to 56% under the reaction conditions of 60 ° C.

Relation between production amount of fatty acid methyl ester and time when steel slag (LD slag) is used as a catalyst
The time change of the methyl-ester production amount with respect to 100g of fats and oils is shown. Table 3 shows methyl ester exchange reaction conditions. It can be seen that the same steelmaking slag as LD slag 2 is fired in Ar (LD slag 3), and the methyl ester exchange reaction time increases to 82.4% in 9 hours.

Production of fatty acid methyl ester when steelmaking slag lump (LD slag 4) stored under dry conditions is used as a catalyst immediately after crushing within 1 month after brewing LD slag 4 in FIG. The steel slag lump stored in the dry condition within 10
The methyl ester exchange reaction conditions for 100 g of fats and oils are shown. In LD slag 4, which was pulverized and heat-treated, a steelmaking slag lump, the methyl ester content increased to 96% under the reaction conditions of 60 ° C. for 6 hours. A significant increase in the reaction rate was obtained compared to 59.4% for 6 hours of LD slag 3.

  INDUSTRIAL APPLICABILITY The present invention can be used for production of fatty acid methyl esters as biodiesel fuel, and is effective in reducing catalyst costs by using steel slag as a catalyst. In addition, even if there are uses such as cement raw materials, roadbed materials, and soil improvement materials, it is possible to provide uses of excessively supplied steel slag, and to expand the availability of steel slag. Furthermore, by using the present invention for the production of fatty acid methyl esters as biodiesel fuel using vegetable oil as a raw material, it is possible to reduce carbon dioxide emissions of greenhouse gases, which are the cause of global warming, and to use for the prevention of global warming it can.

Catalytic properties for fatty acid methyl esterification of blast furnace slag and steelmaking slag

Claims (2)

Blast furnace slag discharged from steelworks is used as a catalyst by dry cooling treatment without using water , or steel slag that is gradually cooled in air is treated with high temperature in an inert gas to increase the activity as a catalyst, A method of producing fatty acid methyl esters to be biodiesel fuel by transesterifying fats and oils with methanol by using as a catalyst .
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