Issue 25/2012 - Advances in butadiene production technology

Butadiene is one of the most important components of C4 fraction, second only to ethylene and propylene in petrochemical olefin raw materials, mainly used in the synthesis of polybutadiene rubber, styrene-butadiene rubber, nitrile rubber and other products, in addition to the production of adiponitrile, hexamethylenediamine, nylon 66, 1,4-butanediol and other organic chemical products and used as a binder, gasoline additives, etc.
, very widely
used.
At present, the sources of butadiene mainly include C4 extraction method, by-product of ethylene cracking and C4 alkane or olefin dehydrogenation, of which C4 extraction of ethylene cracking by-product is the main production method
.

First, ethylene cracking by-product C4 extraction method

According to the different solvents used, the production of butadiene by C4 extraction by-product of ethylene cracking can be divided into three types
: acetonitrile method (ACN method), dimethylformamide method (DMF method) and N-methylpyrrolidone method (NMP method).

1.
ACN process ACN process is represented by the Japanese JRS company process
, which uses acetonitrile containing 10% water as the solvent and adopts two-stage extraction distillation
.
The technical characteristics are low boiling point, low extraction and stripping operating temperature, easy to prevent butadiene self-polymerization; Stripping can be operated at high pressure, eliminating the need for butadiene gas compressors; Low viscosity, high plate efficiency, small actual number of plates, etc
.

Sinopec Yanhua Company and PetroChina Lanhua Company independently developed complex tower and thermal coupling technology, shortening the process flow, reducing phase transition, and greatly reducing energy consumption
.
PetroChina Jilin Petrochemical cooperated with Qingdao Ecos Technology Engineering Co.
, Ltd.
to develop a unique new technology for process integration and energy saving, referred to as QJ-ACN technology
, based on the domestic ACN process.
Using this technology, a batch of butadiene plants have been reconstructed, transformed and newly built in Jilin, Gaoqiao, Panjin and other places, and good economic benefits
have been received.
Drawing on the production technology of separation of butadiene in foreign wall towers, Qingdao Ecos Technology Engineering Co.
, Ltd.
proposed a double partition integration process, using aqueous acetonitrile as a solvent to separate butylene from C4 mixture by extractive rectification and removing butyne and recombinant fractions to obtain crude 1,3-butadiene, so that the traditional two extraction rectification operations and partial decombinant sub-operations are completed in one column, which has the characteristics of
low investment, simple operation and low energy consumption.

2.
DMF method DMF method
is represented by the process developed by Zeon company in Japan, which is characterized by strong adaptability to raw material C4, and the butadiene content can produce qualified butadiene products
in the range of 15%~60%.
。 In recent years, the research of Ruion mainly focuses on the autopolymerization of anti-butadiene, and its technical points are mainly two: first, the use of new polymerization inhibitors; Second, through the control system, the concentration of polymerization inhibitor in the recovered extractant is determined, and the amount
of polymerization inhibitor added in the production process is dynamically changed according to this concentration.
The polymerization inhibitors used can be nitrite, dialkyl hydroxylamine, phosphorus-containing compounds, and polymerization inhibitors can be used alone or mixed, generally dissolved in water or the extractant DMF is added to the system
.

Sinopec Yanhua Company has formed a DMF method design and accounting system with independent intellectual property rights, butadiene screw compressor assembly and maintenance technology, butadiene anti-autopolymerization technology and analysis and testing technology, and transferred 50,000 tons of complete sets of technology to Maoming Petrochemical Company
.

Yangzi Petrochemical ensured the high-load stable operation of the butadiene plant through equipment technical transformation and other measures, and the main measures adopted were: the series operation of the two reboilers of the first extraction distillation column solvent A / B was changed to parallel operation, so that the two reboilers realized online switching and online cleaning, ensuring the smooth operation of the plant; Replace the height of the debutor, the spacing between the bottom gaps, the height of the weir, increase the opening rate and replace the floating valve of the tower plate, so that the processing capacity of the device is increased by 10%~20%; Through the application of control loop transformation and optimization control software, the operation of the device is more stable and reliable; Optimization of polymerization inhibitors reduces the amount of
additives.

In addition, in order to prevent butadiene self-polymerization, Daqing Petrochemical, Qilu Petrochemical and other companies have also innovated
in process improvement, optimized operation, automatic control, energy saving and consumption reduction.

3.
NMP method process NMP method is successfully developed by BASF in Germany, and its process
is characterized by excellent solvent performance, low toxicity and biodegradability; The range of raw materials is wide, and the purity of the product can reach 99.
7%~99.
9%.

BASF has improved the traditional butadiene extraction process and developed a new process for the first extraction and rectification of butadiene in the rectification column next door: the first extraction distillation column adopts the rectification column next door, and the first extraction part adopts a new process of combining the next tower with the extraction scrubber and solvent degassing tower, and the extraction solvent adopts an aqueous NMP solution, and crude 1,3-butadiene
can be obtained by separation.
This technology eliminates the need for compressors and fully considers the comprehensive utilization of heat of high-temperature circulating solvents, so that energy consumption is greatly reduced
.

UOP and BASF jointly developed a combined butadiene extraction process, that is, selective hydrogenation and a stage of extractive distillation combined technology, combining UOP's alkyne selective hydrogenation process (KLP process) with BASF's butadiene extraction and distillation process, first selectively hydrogenating alkynes in the C4 fraction, and then using extraction distillation technology to recover 1,3-butadiene
from butane and butene.

Sinopec Beijing Research Institute of Chemical Industry has developed a process
for selective hydrogenation of alkynes to produce butadiene.
The mixed C4 fraction is first hydrogenated in the liquid phase to remove alkynes, and after hydrogenation, the logistics gasification enters the extraction column to remove butane and butylene
.
The non-condensable gas and C4 extraction liquid contained in the top of the extraction tower enter the degassing tower, and light components
containing hydrogen, methane, propane and propylene are separated from the top of the degassing tower.
C4 extraction liquid is extracted from the degassing tower kettle, part of which is produced, and the rest is returned to the extraction tower as reflux, the C4 fraction extracted from the extraction tower enters the solvent recovery tower, crude butadiene is produced at the top of the tower, and 1,3-butadiene is obtained after further rectification, and the solvent extracted from the tower can be recycled
.

Second, C4 alkane or olefin dehydrogenation

BASF AG S.
Krone et al.
invented a series of methods for preparing butadiene from n-butane, using which high yield butadiene
can be obtained.
SK Energy Co.
, Ltd.
Zheng Yingmin et al.
invented a zinc ferrite catalyst and a method for
preparing 1,3-butadiene using this catalyst.

Yu Yuankun and others of Zibo Qixiang Tengda Chemical Co.
, Ltd.
invented a method
for preparing butadiene by oxidative dehydrogenation of axially fixed bed butene.
By butene, air and water vapor in the axial fixed bed reactor oxidative dehydrogenation reaction to generate butadiene, axial fixed bed reactor has two sections, the process equipment is successively composed of an axial fixed bed reactor, an inter-section heat exchanger, a two-stage axial fixed bed reactor, waste heat boiler and a post-heat exchanger, and the reactor is filled with an iron-based catalyst
。 The ingredient water vapor used in a section of the reactor reacts with a section of the inter-section heat exchanger to generate gas heat exchange and heating, and then mixes with a section of ingredient butene and air to reach the inlet temperature of a stage of the reactor, and enters a section of the reactor for reaction; After the heat exchange and cooling of the inter-stage heat exchanger, the generated gas is mixed with the second-stage feed butene and air to reach the inlet temperature of the second-stage reactor, and enters the second-stage reactor for reaction
.

III.
Others

Wang Yingchun of Sinopec Qilu Petrochemical Company and others invented a method
for the utilization of residual alkyne-rich mixed hydrocarbons in a butadiene extraction device.
Through the fixed-bed hydrogenation reactor with a circulation device, the mixture rich in alkynes is selected to be hydrogenated under the action of the catalyst, so that the alkynes or even butadiene react to remove alkynes or even butadiene, and according to different needs through the combination of different numbers of reactors and control different process conditions, so that the reaction products can be used as fuel, and 1-butene and other monoolefins can be further recovered, or only returned to the 1-butene device to recover 1-butene
.

Li Dongfeng of Sinopec Beijing Research Institute of Chemical Industry and others invented a method for the utilization of exhaust gas from butadiene extraction unit, the steps of which include boosting, condensation, hydrogenation and refrigeration
.
wherein the exhaust gas compressor in the boost, condensing and refrigeration system adopts a two-stage compression compressor driven by the same motor, and each section is independently boosted by the system; The compressor first stage is the exhaust gas raw material boost, and the second section of the compressor is the refrigerant boost of the refrigeration system, and the two systems do not affect each other, which greatly saves equipment investment
.