The present disclosure provides processes for the purification of 2,5-furandicarboxylic acid (FDCA). The present disclosure further provides crystalline preparations of purified FDCA, as well as processes for making the same. In addition, the present disclosure provides mixtures used in processes for the purification of FDCA.

The present disclosure provides processes for the purification of 2,5-furandicarboxylic acid (FDCA). The present disclosure further provides crystalline preparations of purified FDCA, as well as processes for making the same. In addition, the present disclosure provides mixtures used in processes for the purification of FDCA.

Provided is a method for producing an unsaturated aldehyde including subjecting an alkene to partial oxidation using a fixed bed multi-tube reactor to produce the corresponding unsaturated aldehyde, in which n catalyst layers (n is 2 or more) in a gas flow direction in a reaction tube are provided, when a filling length of the catalyst layers from a first catalyst layer to an (n-1)th catalyst layer from a gas inlet side of the reaction tube is L, and a filling length of an nth catalyst layer from the gas inlet side of the reaction tube is Ln, a relationship between L and Ln satisfies the following equation (1):

[00001]$\begin{array}{cc}1<L\text{/}\mathrm{Ln}\le 3,& \left(1\right)\end{array}$ and a composition of a catalytically active component contained in the catalyst layers from the first catalyst layer to the (n-1)th layer from the gas inlet side of the reaction tube is different from a composition of a catalytically active component contained in the nth catalyst layer from the gas inlet side of the reaction tube.

Provided is a method for producing an unsaturated aldehyde including subjecting an alkene to partial oxidation using a fixed bed multi-tube reactor to produce the corresponding unsaturated aldehyde, in which n catalyst layers (n is 2 or more) in a gas flow direction in a reaction tube are provided, when a filling length of the catalyst layers from a first catalyst layer to an (n-1)th catalyst layer from a gas inlet side of the reaction tube is L, and a filling length of an nth catalyst layer from the gas inlet side of the reaction tube is Ln, a relationship between L and Ln satisfies the following equation (1):

[00001]$\begin{array}{cc}1<L\text{/}\mathrm{Ln}\le 3,& \left(1\right)\end{array}$ and a composition of a catalytically active component contained in the catalyst layers from the first catalyst layer to the (n-1)th layer from the gas inlet side of the reaction tube is different from a composition of a catalytically active component contained in the nth catalyst layer from the gas inlet side of the reaction tube.

A catalyst comprising molybdenum, bismuth, iron, and nickel, wherein a proportion of a surface concentration of the nickel to a bulk concentration of the nickel is 0.60 to 1.20.

A catalyst comprising molybdenum, bismuth, iron, and nickel, wherein a proportion of a surface concentration of the nickel to a bulk concentration of the nickel is 0.60 to 1.20.

The present invention relates to a catalyst for oxidative dehydrogenation of butene and a method for producing the same. The catalyst for oxidative dehydrogenation of butene has a large amount of Mo—Bi phase acting as a reaction active phase on the surface, and therefore, can exhibit high catalytic activity, high conversion rate and high butadiene selectivity in the oxidative dehydrogenation of butene.

The present invention relates to a catalyst for oxidative dehydrogenation of butene and a method for producing the same. The catalyst for oxidative dehydrogenation of butene has a large amount of Mo—Bi phase acting as a reaction active phase on the surface, and therefore, can exhibit high catalytic activity, high conversion rate and high butadiene selectivity in the oxidative dehydrogenation of butene.

The present disclosure provides processes for the purification of 2,5-furandicarboxylic acid (FDCA). The present disclosure further provides crystalline preparations of purified FDCA, as well as processes for making the same. In addition, the present disclosure provides mixtures used in processes for the purification of FDCA.

The present disclosure provides processes for the purification of 2,5-furandicarboxylic acid (FDCA). The present disclosure further provides crystalline preparations of purified FDCA, as well as processes for making the same. In addition, the present disclosure provides mixtures used in processes for the purification of FDCA.