What are the economic benefits and technical approaches for producing sec-butanol or methylethyl ketone from mixed C4 hydrocarbons?

I would like to ask this question too; I wonder if any teacher could give me some guidance

MEK is an organic solvent and fine chemical raw material with excellent performance; it features moderate volatility, strong solvating power, and low viscosity. It is miscible with various hydrocarbon solvents and is widely used in areas such as lubricant dewaxing, coatings, adhesives, inks, magnetic tapes, pharmaceuticals, and electronic components. In 2000, the global total production capacity for both types was 1.2 million tons; of this, Europe accounted for 30%, the United States for 28%, the Asia-Pacific region for 18%, Japan for 16%, South America for 5%, and South Africa for 3%. In 2000 and 2001, the global demand for both type A and type B products was 950,000 tons. Of this amount, coatings accounted for 63%, adhesives for 11%, magnetic media for 7%, chemical intermediates for 5%, dewaxing agents for 5%, printing inks for 2%, and other products for 7%. The demand for both type A and type B in the Chinese market is increasing at a rate of 20% per year; by 2000, the demand reached 110,000 tons, with imports exceeding 100,000 tons, and by 2005 the demand had risen to 150,000 tons. Most companies, including ExxonMobil Chemical and Shell Chemical, primarily use n-butylene to produce methylethylene through the same pathway. This two-step synthesis method involves the hydration of n-butylene to produce sec-butanol, which is then dehydrogenated to yield methyl ethyl ketone; this process has become the dominant technique for producing methyl ethyl ketone on an international scale.

This post was last edited by lhyhzc on 2009-5-29 09:55. Economic benefits: The higher the content of tetraenoic hydrocarbons in the raw material, the lower the energy consumption required for butene concentration, and thus the lower the production costs； A high content of isobutylene in tetraalkenes also increases the amount of extractant required for butene concentration. At the same time, the reaction rates of the three butene components (1-butene, cis-2-butene, and trans-2-butene) also differ. Therefore, different raw materials result in varying consumption of equipment and energy, which in turn leads to differences in costs. The price of raw materials mainly depends on the price of liquefied petroleum gas, and is therefore closely linked to international crude oil prices. The products are aimed at end-users, and in most markets their market overlaps with that of other solvent products, which can sometimes replace each other. Under the influence of all these factors, the specific economic benefits of devices Type A and Type B need to be analyzed individually. Technical route: The same-process unit for methylethyl is mainly composed of four parts: butylene concentration, sec-butanol synthesis, sec-butanol purification, and methylethyl synthesis and purification. Butene concentration. After extraction distillation and stripping in sequence on a mixed C4 fraction, the butene concentration can reach over 97%. Synthesis of butyl alcohol. Butene that meets the process requirements is heated and then combined with process water that has been pressurized and heated, and together they enter the hydration reactor. There, under the action of an acidic sulfonated resin catalyst, at specific temperature and pressure conditions, a hydration reaction takes place to produce sec-butanol. The aqueous phase after the reaction is cooled in a heat exchanger and a separator, then sent to a deionized water unit for regeneration; after fresh ion-free water is added, the hydration reaction is carried out again. Since the one-way conversion rate of the hydration reaction is only about 8%, the gas phase after the reaction contains not only sec-butanol but also a large amount of unreacted butylene. After condensation and pressure reduction, this gas enters the butane removal system to recover the unreacted butylene, which is then used as feedstock for the hydration reaction in a cyclic manner. Pentan-2-ol purification. Crude sec-butanol is sent to the distillation unit to remove the by-products of the hydration reaction, and then to the sec-butanol purification tower. The distillate from the top of the tower, which is pure sec-butanol with a purity of over 99%, is condensed and sent to the finished product tank. A and B are synthesized and refined together. Butyl alcohol from the finished product tank is vaporized by heating, and then heated to a temperature close to the reaction temperature before entering the dehydrogenation reactor. There, under the action of a copper catalyst, a dehydrogenation reaction takes place. The reaction products other than hydrogen are condensed and sent to the distillation system for further processing; both methane and ethane are distilled from the top of the tower, and after cooling, the desired methane and ethane products are obtained.

I’ll take on you on the 4th floor! Thank you for your explanation; I’ve learned a lot from it!

The key process in both technologies is butylene hydration; the main production issues arise during this hydration process, with the biggest problem being the catalyst, which often leaks out. The equipment used in the hydration process requires high-grade materials, with 307L and 904 being suitable choices. There are over 10 sets of such systems of type A and B in China, with the design still done by the Third Research Institute of Chemistry.

n-Butylene is converted into sec-butanol through the action of heat-resistant sulfonated cation exchange resins; the reaction takes place under three-phase conditions, at a temperature of 150–170°C and a pressure of 5.0–7.0 MPa. Under these conditions, n-butylene is in a supercritical state, which allows sec-butanol to be extracted from the liquid reaction mixture, making it easier to separate sec-butanol via distillation. The molar ratio of process water to n-butylene in the feed is approximately 1.5–2.0:1. Since the one-pass conversion rate of n-butylene is only 5%–10%, an excess of process water is used in the actual reaction; this helps to improve the selectivity for sec-butanol and to suppress the formation of by-products.

The benefits of having both A and B are not very good at the moment. Let’s take a look at our hybrid carbon 4 reaction distillation method for the hydrolytic production of sec-butanol – this technology is used to manufacture fuel-grade sec-butanol, and there are broad market prospects for it. The production process is short, and the investment required is relatively low

In the same production process for Methyl Ethyl Ketone, it is first necessary to carry out an etherification reaction on the naphtha C4 fraction in order to remove isobutylene from it. The C4 fraction after etherification is then subjected to acetonitrile extraction to isolate butylene, from which n-butylene is obtained. N-Butylene reacts with water to produce sec-butanol; this sec-butanol is purified and subsequently subjected to a dehydrogenation reaction to yield Methyl Ethyl Ketone and hydrogen gas. The final product, Methyl Ethyl Ketone, is obtained through further purification and separation. The currently mature and environmentally friendly industrial production technology for MEK is the direct aqueous synthesis of sec-butanol using resin catalysts. The direct hydration process of n-butylene is as follows: n-butylene reacts directly with water in the presence of a resin catalyst at a pressure of 8.0 MPa and a temperature of 165°C to produce sec-butanol: H+ C4H8 + H2O → C4H9OH. The crude sec-butanol obtained from this reaction is sent to a distillation unit where impurities are removed to yield pure sec-butanol, which is then forwarded to the dehydrogenation stage. The resulting refined sec-butanol is dehydrogenated over a copper-based catalyst to produce MEK: C4H9OH → CH3COC2H5 + H2↑

Hydrogenation of fuel-grade butanol using reactive distillation – vast market prospects!

What technology is most commonly used in the current production process of butyl alcohol? ?