Abstract: The present invention relates to a method for preparing an aromatic dialdehyde, comprising, a) a step of gas phase oxidation reaction for preparing aromatic dialdehyde from dimethyl benzene; b) a step of separation for selectively recovering crude aromatic dialdehyde of molten phase from the reaction product of the step (a); and c) a step of purification for obtaining highly pure aromatic dialdehyde by purifying said crude aromatic dialdehyde, and a manufacturing system used for the preparation method. The method for preparation of the aromatic dialdehyde according to the present invention is simple, effective, and advantageous in that highly pure aromatic dialdehyde can be continuously prepared.

Abstract: The present invention relates to a novel method for preparing a catalyst of the formula (1), WOx wherein, W represents tungsten atom, O represents oxygen atom x represents a value determined by oxidative state of W, for partial oxidation of methylbenzenes, the method comprising: (a) a step of preparing tungsten oxide slurry by wet milling; (b) a step of supporting the slurry obtained in the step (a) on fire-resistance inorganic carrier by impregnation; (c) a step of drying the catalyst obtained in the step (b); and (d) a step of calcining the dried catalyst obtained in the step (c), and can reduce the reaction temperature on the basis of equivalent yield in the preparation of corresponding aromatic aldehyde from methylbenzenes since the catalyst has increased the surface areas compared to the conventional one, and thus has high conversion rate.

Abstract: The present invention relates to a novel method for preparing a catalyst for partial oxidation of methlybenzenes, comprising, (a) a step of preparing a solution or slurry of the compounds comprising tungsten (b) a step of supporting the solution or slurry obtained in the step (a) on inorganic carrier; (c) a step of drying the catalyst obtained in the step (b); and (d) a step of calcining the dried catalyst obtained in the step (c), characterized in that the ratio of the pore volume of inorganic carrier and the volume of the solution or slurry in the step (b) is 1:09˜1.1, and the catalyst provides superior aromatic aldehydes selectivity to those prepared by the conventional impregnation or heat evaporation method over a wide range of conversion rate.

Abstract: A hydraulic wheel system is provided which comprises a disc, a first piston, a wheel, a tire, a dismount button, and a wheel mounting member. The disc is provided with a first cylinder and a second cylinder communicating with each other. The first piston is slidably disposed within the first cylinder. The wheel is coupled to the disc so that a rotational force of the disc is transmitted to the wheel. The dismount button is configured to move the first piston. The wheel mounting member is provided in the disc. A second piston that is slidably disposed within the second cylinder is integrated with the wheel mounting member. The wheel mounting member is elastically supported by an elastic member in a direction opposite to the predetermined direction, and it is configured to be selectively connected to the wheel in response to a movement thereof.