Abstract: A process for producing (meth)acrylic acid while preventing a polymerization of (meth)acrylic acid using a polymerization inhibitor solution, comprising the steps of: obtaining a (meth)acrylic solution containing formaldehyde from any step of the process for producing (meth)acrylic acid to use as a solvent of the polymerization inhibitor solution, and adding phenothiazine or derivatives thereof and/or hydroquinone or derivatives thereof to the (meth)acrylic solution containing formaldehyde to obtain polymerization inhibitor solution so that the polymerization inhibitor solution contains 0.1 mass % to 3 mass % of phenothiazine or derivatives thereof and/or 0.1 mass % to 10 mass % of hydroquinone or derivatives thereof, wherein the polymerization inhibitor solution contains 10 ppm to 5000 ppm (based on mass) of formaldehyde.

Abstract: The present invention provides an industrially easy and economical method for purification of acrylic acid which enables to efficiently eliminate impurities from a crude acrylic acid containing aldehydes as the impurities while the formation of acrylic acid polymer is inhibited. The method for purification of acrylic acid includes the step of distilling a crude acrylic acid which is charged with an aldehyde treatment chemical, wherein the concentration ratio of furfural to acrolein by weight in the crude acrylic acid is adjusted so as to satisfy the following equation: (furfural concentration by weight)/(acrolein concentration by weight)?100.

Abstract: This invention discloses a method for producing maleic anhydride comprising an azeotropic distillation step to dehydrate a crude maleic acid-containing aqueous solution, which method is characterized by as an azeotropic solvent (1) using an organic solvent exhibiting a maximum dissolving concentration of the organic solvent in water in the range of 0.1-5% by weight at a temperature of 20° C. According to this invention, it is made possible to prevent the occurrence of a blocking substance, allow a continuous operation for a long time, and remove by-produced acid components by a process of distillation for azeotropic dehydration.

Abstract: This invention concerns a method for absorbing acrylic acid, characterized by supplying an acrylic acid-containing reaction gas component obtained by the reaction of catalytic gas phase oxidation to an acrylic acid absorption column and advancing a high boiling inert hydrophobic organic liquid into counter-flow contact with said reaction gas in said acrylic acid absorption column with the mass flow rate of the organic liquid fixed in the range of 0.2-7.0 times the mass flow rate of the acrylic acid in the reaction gas thereby absorbing acrylic acid in said organic liquid and obtaining an acrylic acid-containing solution including a low boiling substance in the range of 0.7-7.5 wt % based on the weight of bottom liquid of absorption column.

Abstract: This invention concerns a method for absorbing acrylic acid, characterized by supplying an acrylic acid-containing reaction gas component obtained by the reaction of catalytic gas phase oxidation to an acrylic acid absorption column and advancing a high boiling inert hydrophobic organic liquid into counter-flow contact with said reaction gas in said acrylic acid absorption column with the mass flow rate of the organic liquid fixed in the range of 0.2-4.5 times the mass flow rate of the acrylic acid in the reaction gas thereby absorbing acrylic acid in said organic liquid and obtaining an acrylic acid-containing solution and a method for purifying acrylic acid, comprising a step for purifying the acrylic acid-containing organic liquid obtained by the step mentioned above. By this invention, a product of acrylic acid containing a low boiling substance at a low concentration can be produced.

Abstract: This invention concerns a method for absorbing acrylic acid, characterized by supplying an acrylic acid-containing reaction gas component obtained by the reaction of catalytic gas phase oxidation to an acrylic acid absorption column and advancing a high boiling inert hydrophobic organic liquid into counter-flow contact with said reaction gas in said acrylic acid absorption column with the mass flow rate of the organic liquid fixed in the range of 0.2-7.0 times the mass flow rate of the acrylic acid in the reaction gas thereby absorbing acrylic acid in said organic liquid and obtaining an acrylic acid-containing solution including a low boiling substance in the range of 0.7-7.5 wt % based on the weight of bottom liquid of absorption column.

Abstract: This invention discloses a method for producing maleic anhydride comprising an azeotropic distillation step to dehydrate a crude maleic acid-containing aqueous solution, which method is characterized by as an azeotropic solvent (1) using an organic solvent exhibiting a maximum dissolving concentration of the organic solvent in water in the range of 0.1-5% by weight at a temperature of 20° C. According to this invention, it is made possible to prevent the occurrence of a blocking substance, allow a continuous operation for a long time, and remove by-produced acid components by a process of distillation for azeotropic dehydration.

Abstract: This invention concerns a method for absorbing acrylic acid, characterized by supplying an acrylic acid-containing reaction gas component obtained by the reaction of catalytic gas phase oxidation to an acrylic acid absorption column and advancing a high boiling inert hydrophobic organic liquid into counter-flow contact with said reaction gas in said acrylic acid absorption column with the mass flow rate of the organic liquid fixed in the range of 0.2-4.5 times the mass flow rate of the acrylic acid in the reaction gas thereby absorbing acrylic acid in said organic liquid and obtaining an acrylic acid-containing solution and a method for purifying acrylic acid, comprising a step for purifying the acrylic acid-containing organic liquid obtained by the step mentioned above. By this invention, a product of acrylic acid containing a low boiling substance at a low concentration can be produced.

Abstract: The present invention provides an industrially easy and economical method for purification of acrylic acid which enables to efficiently eliminate impurities from a crude acrylic acid containing aldehydes as the impurities while the formation of acrylic acid polymer is inhibited.

Abstract: Provided is a structure of a front body of an automobile comprising a steering system which can prevent a steering gear case from coming in contact with a road surface during running on a bad road or the like even if an under cover is not provided, and which can reduce costs, weight and size, and can provide proper (small) changes in the toe angle and the driver with a smooth sense of steering. In the front body of an automobile in which the suspension arm (lower control arm) and the steering gear case (pinion case) are attached to the suspension frame and at least a part of the steering gear case (for example, a pinion case) is placed below the suspension frame, a downward protrusion which protrudes downward and has a face slanted downward toward the rear portion of the automobile body is provided on the bottom portion of the suspension frame.

Abstract: A bump stop seat structure which can achieve a larger cabin space in the room of a vehicle or automobile without sacrificing a bump stroke by suppressing roll angle. In the bump stop seat structure, a stop seat (12) is provided on a housing (6) of an axle (2) of the vehicle in such a manner as to face a bump stop (9) mounted on a body (1) thereof. Further, a flat end face (13), which is nearly level and faces upwardly, is provided on one of opposite side portions of the stop seat (12), which are arranged in the direction of width of the vehicle. Moreover, a convex part (14) projecting to the bump stop (9) is provided only on a part of the other side portion of the stop seat (12). Thus, the convex part (14) is in contact with the bump stop (9) only when the vehicle performs a rolling movement.