KR102325331B1 - Method for isobutylene from tert-butanol - Google Patents

Abstract

The present invention uses a zirconium oxide (ZrO ₂ ) solid acid catalyst with a specific surface area of 30 m ² /g or more in the dehydration reaction of tert-butanol to show high conversion of tert-butanol and high selectivity to isobutylene. An object of the present invention is to provide a method for producing isobutylene capable of suppressing oligomerization and side reactions of isobutylene. Due to the high conversion rate of tert-butanol and the selectivity of isobutylene, there is an economic effect of obtaining high purity isobutylene without adding a separate distillation process.

Description

Method for preparing isobutylene from tert-butanol {Method for isobutylene from tert-butanol}

The present invention relates to a process for preparing isobutylene from tert-butanol.

In general, isobutylene forms tert-butanol or tert-butyl methyl ether through hydration or esterification on the residue (C4 Raffinate-1) after extraction of 1,3-butadiene from the C4 hydrocarbon fraction of naphtha crackers. After that, it is prepared by a method of dissociating it again.

In the case of the dehydration reaction of tert-butanol for the production of isobutylene, relatively few by-products are produced, so a complicated process is not required. The dimethoxylation reaction of tert-butyl methyl ether is a technique widely used industrially, but a purification process is essential because many kinds of by-products are generated.

Among the previously known methods for producing isobutylene, the dehydration reaction of tert-butanol using sulfuric acid at a low temperature may cause corrosion of the equipment and problems with wastewater. In addition, in the case of the method using a strongly acidic ion exchange resin, there is a problem in that the reaction rate is lowered because the reactant tert-butanol and the product isobutylene and water exist in an equilibrium relationship.

In addition, in the case of a method using a solid acid catalyst with high acid strength (zeolite, silica-alumina, etc.), oligomerization of isobutylene is promoted, thereby reducing the selectivity to isobutylene, reducing the thermal stability of the catalyst and reducing utility costs. As it consumes a lot, there are many restrictions on commercialization operation.

For reference, by oligomerization of isobutylene in the dehydration reaction of tert-butanol, diisobutylene (or 2,4,4-trimethyl-1-pentene), triisobutylene (or 2,4,4, 6,6-pentamethyl-2-heptene), etc. may be formed, which not only lowers the selectivity to the desired product isobutylene, but also requires an additional process to separate them, so isobutylene Inhibiting the oligomerization of is advantageous in terms of productivity improvement.

Accordingly, it is necessary to develop a method capable of producing high-purity isobutylene of more than 99.5% without a separation step such as additional distillation while ensuring a yield of 95% or more isobutylene using a solid acid catalyst with weak acidity. is becoming

However, the method for producing isobutylene by the dehydration reaction of tert-butanol proposed so far does not satisfy the high conversion rate of tert-butanol and the high selectivity to isobutylene at the same time, and the oligomerization of isobutylene is not achieved. There are limits that cannot be sufficiently suppressed.

Republic of Korea Patent Publication No. 1104106 (2012.01.03) US Registered Patent No. 4873391 (10.10. 1989) Republic of Korea Patent Publication No. 10-2018-0034066 (2018.04.04)

The present invention provides a method for producing isobutylene that can suppress oligomerization and side reactions of isobutylene while exhibiting high conversion of tert-butanol and high selectivity to isobutylene in the dehydration reaction of tert-butanol it is to do

The present invention, in order to achieve the above object, in _{the presence of a zirconium oxide (Zirconium Oxide, ZrO 2} ) catalyst - a dehydration reaction step of obtaining isobutylene by contacting a reactant in the gas phase including tert-butanol and water vapor with the catalyst There is provided a method for producing isobutylene comprising a.

Hereinafter, a method for producing isobutylene according to an embodiment of the present invention will be described in detail. However, the present invention may be implemented in various different forms, and is not limited by the embodiments described herein.

Unless explicitly stated herein, terminology is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention. Also, as used herein, the singular forms include the plural forms unless the phrases clearly indicate the opposite.

The meaning of 'comprising' as used herein is to specify a particular characteristic, region, integer, step, operation, element or component, and excludes the addition of another particular characteristic, region, integer, step, operation, element, or component. it is not

On the other hand, according to the research of the present inventors, when a zirconium oxide catalyst is used in the production process of isobutylene by the dehydration reaction of tert-butanol, high conversion of tert-butanol and high selectivity to isobutylene are obtained. It was confirmed that oligomerization of isobutylene can also be suppressed.

According to one embodiment of the present invention, in the presence of a zirconium oxide catalyst, a dehydration reaction step of obtaining isobutylene by contacting a reactant in a gas phase including tert-butanol and water vapor with the catalyst, Preparation of isobutylene A method is provided.

The method for preparing isobutylene is a method for preparing isobutylene by dehydration of tert-butanol in the presence of a heterogeneous solid acid catalyst.

In particular, the heterogeneous solid acid catalyst used for the dehydration reaction of tert-butanol is a zirconium oxide catalyst having a ^{specific surface area of 30 m 2 /g or more.}

Meanwhile, according to an embodiment of the present invention, the dehydration reaction may be performed by contacting a reactant in a gas phase including tert-butanol and water vapor with the catalyst. For example, the dehydration reaction may be performed by providing the reactant stream to a fixed-bed reactor loaded with the catalyst to be brought into contact with the catalyst.

In this case, in order to minimize the change in reaction temperature due to the latent heat of the reactant, it is preferable to preheat the reactant and inject it in a vaporized state. And, the reactant in the gas phase includes tert-butanol and water vapor, and in particular preferably contains 50 to 100% by weight of tert-butanol. Specifically, the reactant in the gas phase may include 70 wt% or more, and 87 wt% or less, tert-butanol.

Meanwhile, the dehydration reaction step may be performed at a temperature of 300 to 400 °C and a space velocity (WHSV) of ^{0.01 to 3 h -1 .} And, the dehydration reaction step may be carried out under 0.5 to 5 atmospheres, preferably atmospheric pressure (0 to 1.0 barg). At the normal pressure, there may be a natural pressure drop caused by the catalyst and the device. In addition, the space velocity (WHSV) represents the net mass inflow rate of tert-butanol in the reactant relative to the mass of the catalyst used for the reaction. For the efficiency of the dehydration reaction, the space velocity is preferably ^{0.5 or more and 3 h -1 or less.} do. When the temperature and space velocity of the dehydration step are out of the range, the conversion rate and yield may decrease.

The method for producing isobutylene according to an embodiment of the present invention may exhibit a conversion rate of tert-butanol of 95% or more as it is performed under the above-described steps and conditions. In addition, the method for preparing isobutylene exhibits selectivity for less than 1% isobutylene oligomers (eg, diisobutylene and triisobutylene), so that isobutylene oligomers are minimized, and thus isobutylene high selectivity can be obtained.

The method for producing isobutylene according to the present invention can exhibit high conversion of tert-butanol and high selectivity to isobutylene in the dehydration reaction of tert-butanol, while suppressing oligomerization and side reactions of isobutylene. , enabling the production of isobutylene in high yield.

Hereinafter, preferred embodiments of the present invention will be described in detail, but the scope of the present invention is not limited to the following examples.

manufacturing example

Commercial zirconium oxide particles (extrudate, 5 mm, product number SZ31163, Saint-Gobain, France) were prepared as a catalyst for dehydration of tert-butanol. The specific surface area of the catalyst was 60 m ² /g.

Reference Example 1

Commercial alumina particles (pellets, 3 mm, product number 414069, Sigma-Aldrich, USA) were prepared as a catalyst for dehydration of tert-butanol. The specific surface area of the catalyst was 200 m ² /g.

Reference Example 2

Commercial zirconium sulfate particles (pellets, 3 mm, product number SZ61192, Saint-Gobain, France) were prepared as catalysts for dehydration of tert-butanol. The specific surface area of the catalyst was 130 m ² /g.

Example 1

10 g of tert-butanol dehydration catalyst according to Preparation Example was charged in a fixed bed reactor, and then the catalyst bed was preheated to 360°C. A reactant in the gaseous phase of preheating an aqueous solution containing 85% by weight of tert-butanol ^{was injected into the catalyst bed of the reactor at a space velocity (WHSV) of 1.0 h −1} , and dehydration reaction was performed at a temperature of 360° C. and atmospheric pressure.

Example 2

A dehydration reaction was performed in the same manner as in Example 1, except that the reaction temperature was changed to 380°C.

Comparative Example 1

A dehydration reaction was performed in the same manner as in Example 1, except that the reaction temperature was changed to 250°C.

Comparative Example 2

A dehydration reaction was performed in the same manner as in Example 1, except that the reaction temperature was changed to 450°C.

Comparative Example 3

A dehydration reaction was performed in the same manner as in Example 1, except that the space velocity was changed to 2.0 h ^-1.

Comparative Example 4

A dehydration reaction was performed in the same manner as in Example 1, except that the catalyst was changed to the zirconium sulfate particles of Reference Example 2 and the reaction temperature was changed to 260°C.

Comparative Example 5

A dehydration reaction was performed in the same manner as in Example 1, except that the catalyst was changed to the alumina particles of Reference Example 1.

After 10 hours had elapsed from the start of the dehydration reaction, the product effluent after the decomposition reaction was analyzed by gas chromatography, and the conversion rate and selectivity of tert-butanol were calculated using the following formula. Products other than isobutylene were calculated as oligomers (diisobutylene, triisobutylene, etc.).

[Formula 1]

Tert-butanol conversion (%) = [the number of moles of tert-butanol added - the number of moles of tert-butanol remaining after the reaction]/[the number of moles of input tert-butanol] X 100

[Equation 2]

Isobutylene selectivity (%) = [number of moles of isobutylene produced]/[number of moles of tert-butanol converted] X 100

[Equation 3]

Oligomer selectivity (%) = [number of moles of oligomer produced]/[number of moles of tert-butanol converted] X 100

[Equation 4]

Yield of isobutylene (%) = [number of moles of isobutylene produced]/[number of moles of tert-butanol added] X 100

Based on the results of Table 1, high tert-butanol conversion and isobutylene selectivity were obtained in the zirconium oxide catalyst.

Claims (3)

A dehydration reaction step of obtaining isobutylene by contacting a reactant in a gas phase including tert-butanol and water vapor with the catalyst in the presence of a zirconium oxide catalyst,
The dehydration reaction step is carried out at a temperature of 300 to 400 ℃ and a space velocity (WHSV) of ^{0.1 to 1 h -1, the method for producing isobutylene.} The method for producing isobutylene according to claim 1, wherein the zirconium oxide catalyst has a specific surface area of 30 m ² /g or more. delete