Syngas Based Ethylene Glycol Synthesis Technology
 

Our technology of syngas based ethylene glycol production is shared by Ningbo Fareast Tech Catalyst Engineering Co.,Ltd, China Chengda Engineering Co.,Ltd and Ningbo Institute of Industrial Technology (CNITECH), Chinese Academy of Sciences (CAS).  We are granted for the promotion of for the commercial promotion, who can provide you with ethylene glycol technology package, the core catalyst, the engineering design, the skills training for staffs and the driving services.

The technology is based on the nitric acid reduction technology, which reduces the consumption of raw materials and the burden of waste water treatment; The efficiency is high withan emission concentration of 300-1000ppm; The steam consumption of the EG distillation system is ≤ 2 MT/MT EG; The carbon monoxide consumption is 792NM / MT EG, the hydrogen consumption is1565NM / MT EG and oxygen consumption is 192NM / MT EG which are all very low. The excellent rate of product is 100%, which entered the polyester industry successfully.

 At present, the technology has been applied successfully to Hualu Hengsheng Co., Ltd., more than 10 manufactures has got the technology license. With the concept " the profession comes from intention " we will do our best to improve the added value of coke oven gas.

Development process
We started the research since 2007 with the following process: Carbon monoxide was coupled catalytically first to make oxalate ester which was then hydrogenated to ethylene glycol. In 2011 we established the engineering technology research center with Ningbo Institute of Industrial Technology (CNITECH), Chinese Academy of Sciences (CAS),where we established the scientific experiment and R & D base whose core team consists of 16 scientists (7doctors and 9 masters) including Dr. Yu-Qiao Xiang and Dr. Hong-Feng Yin. This team is mainly engaged in the research and development of ethylene glycol synthesis process.

After eight years of continuous research, a detailed and comprehensive experimental work was carried out including the research and development of catalyst, the research of engineering and mechanism of reaction, the research of the process, the establishment of complete database of physical properties and the separation system.  Many core technologies were mastered such as the  CO based synthesis of oxalate, the oxalate hydrogenation and others which includes: a perfect database of properties; esterification - carbonylation steady closed self-circulation key technology;  the key technology of the recycling of methyl nitrite, carbon monoxide and nitric oxide ; the reactor and its technology for the oxalate synthesis;  the key technology of oxalate synthesis and catalysts preparation for the hydrogenation process.
At the first stage the model test research of 10 MTs / year of synthetic oxalate ester and oxalate hydrogenation was operated successfully , then a pilot work of 300 MTs / year of dimethyl oxalate and dimethyl oxalate hydrogenation was put into production, at last the process software package of 10,000 MTs of CO coupled for oxalate ester and oxalate hydrogenation was completed . 
The engineering technology research center made a huge investment to purchase the most advanced device platform for the testing, evaluation and experiment. The systematic technical research was carried out in terms of the key technology of the ethylene glycol synthesis, the dimethyl oxalate synthesis, the esterification regeneration, the dimethyl oxalate hydrogenation,the ethylene glycol refining and other major processes.
The technology and catalyst of the Hualu Hengsheng’s 50,000MT/year ethylene glycol plant were improved by CNITECH and us from April 2014 to May 2015. From June 2015 till now, the device was operated at full capacity continuously, stably and safely with 100% excellent quality at low production cost, which brought a lot of benefits in the market downturn. A major breakthrough of the ethylene glycol production technology was gained compared with the old device.

The indirect synthesis of ethylene glycol by syngas is a technical and economical route. In the ethylene glycol synthesis the raw materials are hydrogen, carbon monoxide, oxygen and nitrogen that meet the requirement, and it is produced indirectly . The main reactions involved are
Nitrogen oxide is formed by sodium nitrite; The reduction reaction of nitric acid;The nitrogen oxide react with oxygen and methanol to form methyl nitrite (MN);The methyl nitrite (MN) reacts with carbon monoxide to form dimethyl oxalate (DMO) by gas phase synthesis;The dimethyl oxalate (DMO) is hydrogenated by gas phase to form Ethylene Glycol (EG).
the NO is prepared by the reaction of sodium nitrite with nitric acid when driving but it is supplied by the reduction of nitric acid in the following normal production.
The main reaction equations are as below:

（1）NO preparation :
3NaNO2+2HNO3 2NO+3NaNO3+H2O（for driving）
2NO+3CH3OH+HNO3 3CH3ONO（MN）+2H2O（normal supplement）

（2） Esterification reaction
4NO+O2+4CH3OH 4CH3ONO（MN）+2H2O

（3）Carbonylation reaction
2CH3ONO+2CO CH3OOCCOOCH3（DMO）+2NO

（4）Hydrogenation reaction
CH3OOCCOOCH3+2H2 CH3OOCCH2OH（MG）+CH3OH
CH3OOCCH2OH+2H2 HOCH2CH2OH（EG）+CH3OH

（5）Total reaction equation
2CO+1/2O2+4H2→HOCH2CH2OH（EG）+H2O

Technical characteristics
Compared with other ethylene glycol technology, our technology by synthetic gas is with the following advantages and characteristics:
1.The esterification is safe and reliable
Considering the complexity of the esterification reaction, a special structure of the distributor is designed on the basis of lessons learned from the accident of similar devices, thus eliminating the potential safety hazard. Gas-liquid parallel flow packed tower is used for the esterification . In the case of the same tower height, the rotating vortex internals are increased to improve the reaction efficiency, saving the investment; with the co-current form the liquid-gas ratio is small, the operation is flexible and the system resistance is reduced, this is good for the normal operation of the circulation compressor ,which improves the surge interval of the compressor.
2. By using nitric acid reduction technology, the consumption of raw materials is reduced, the waste is made profitable and the load of the waste water treatment is also reduced.
At present, the large-scale industrialization process of coal-based glycol is mainly using the reaction of alcohols with NO and NO₂ to produce methyl nitrite (MN). MN is oxidized by Pd catalyst to get dimethyl oxalate (DMO),and then by hydrogenation to get EG. Among these total processes the methyl nitrite (MN) regeneration tower plays a very important role. In the current process, some nitric acid is added to the system to produce sufficient NO and NO₂. The unreacted nitric acid-containing solution requires further treatment to reduce and neutralize the nitric acid. In this process if the temperature and concentration are controlled improperly, this not only affects the technological index, but also makes it possible to explode, so the reduction of nitric acid is a key point in EG production and the technical requirements are high. In the early technology, the addition of nitric acid was mainly accomplished by one or more reactors connected together. For example, for an annual output of 25,000 MTs / year ethylene glycol plant, nitric acid reduction plant needs to be supplied by 5-8m³ / h nitric acid absorption solution (the mass concentration approx. 5-8%), while the nitric acid concentration in the discharge reaches 0.7-1%, followed by the neutralization by the lye, this is a serious waste and lead to a high pressure of environmental protection and the increasing cost of processing. This type of kettle-type nitric acid purification system has the following shortcomings: 1, due to the reaction needs sufficient reaction residence time, it needs to use more than three 30-100m³ capacity of the reactor, which lead to an large area of floor space, low space utilization and high investment in equipment; 2. due to the introduction of mechanical agitation, MN is easy to leak in the seal part of the mixing shaft which will cause high security risks; 3, The amplification effect of the large-volume reactor is obvious, the mixed reaction is not uniform and the purification is not complete, which lead to the current inefficiency and high emission..
In recent years, the nitric acid reduction technology has been greatly improved, the essence of the core is the nitric acid can be degraded to 0.1% or less by a catalyst at low temperatures (85-100 ℃), the basic nitric acid purification target is realized, but the technology package of this set is expensive, the transfer price of 300,000MTS EG device technology package reached more than 20million yuan, the investment in equipment cost is more than 20 million yuan, and the catalyst life is short, only 1 year, so the annual cost of catalyst is more than 10 million yuan.
With the valuable experience of nitrogen oxide treatment and nitric acid enrichment, our team developed the new technology specially for the EG nitric acid purification system based on the distillation technology and equipment of the hydrolysis, esterification and other reactions. The principle is to use a combined reaction purification tower. The reaction gas including part of the NO and NO₂ removal of DMO reacts completely with the nitric acid supplied by the system. A concentration section, a circulation absorption section and a depth purification section are passed sequentially. The MN concentration in the final outlet gas is raised to 12-16%, while the nitric acid content in the effluent is reduced to less than 1000ppm. Compared with the widely used multi-stage kettle-type nitric acid reduction device and the catalytic reduction nitric acid process, this technology is with the following outstanding advantages:
1), Short process, it covers an area of only one-tenth of the kettle-type purification system;
2), High efficiency, the emission concentration is 300-1000ppm (which is the lowest emission concentration);
3),Low investment, for 50,000 tons EG the total investment is only 4-5 million Yuan (for 500,000 tons the investment is about 300-40 million Yuan);
4), No need of catalyst, no additional maintenance costs every year, long device life;
5), safe and reliable process, no hidden danger.
Currently Hualu Hengsheng ‘s 50,000 MTs EG demonstration device are being operated successfully;
Xinjiang Tianye’s 50,000 tons EG plant are also with this technology;
Hualu Hengsheng’s ongoing 500,000 tons EG device are intended to use this technology.
3, A reasonable heat recovery system was set, making full use of the heat from synthetic reaction, which improved the comprehensive utilization of raw materials and achieved significant economic benefit.
4,1 The water generated from the esterification unit will have a negative impact on the coupling catalyst, so the reactant must be dried to remove the water before entering the synthesis tower. In the similar domestic devices the molecular sieve are generally used to absorb and delete the water.
The disadvantage is: higher system resistance, longer process, higher power consumption;
although the automation is realized, the failure rate is high and frequent switching is needed;
High investment :For a 200,000 MTs of equipment the investment is about 20 million yuan,
High risk: when the water is absorbed by the molecular sieve the MN gas is also absorbed, the MN is easily to be enriched locally in the regeneration process, forming the mixed explosive gas.
Our ethylene glycol synthesis technology with independent intellectual property rights is used to remove the impurities and water. An effective solution is found to remove the water generated in the esterification process by a tower spray adsorption purification unit, which protects the coupling synthetic catalyst and extends the cycle life.
 4.2 Carbonylation and hydrogenation

1, With our ethylene glycol technology we develop an efficient composite reactor based on the traditional reactor , this will avoid the poor heat transfer effect of the fixed bed column tube reactor , which is easy to lead to temperature runaway. The characteristics of the reactor are: The deflection baffle between the tube sheet at the hot water side is designed with a ring spindle type , which optimizes the torsion form of the hot water, thus it improves the heat transfer efficiency and the utilization of catalyst and reduced the waste.
2.The reaction heat from the coupling is fully made use of, there is no need of extra steam before the synthetic feed gas enters the reactor, thus reducing the steam consumption of the device.   
3、During the DMO hydrogenation unit, we uses a reasonable process configuration by our ethylene glycol technology, which reduces the amount of hydrogen circulation greatly and lowering the energy consumption of hydrogen compression. 
4.3 Rectification
1 In the traditional rectifying tower the velocity in the center is fast but in the tower wall it is slow. Considering this we use a unique technology. The heterogeneous openings are made in the rectifying tower, so the flow rate in the center is slow, but fast along the tower wall, which enhances the mass transfer effect, reduces the energy consumption and saves the investment.
2、By the distillation, adsorption and deep hydrogenation coupling technology, the recovery rate of EG reaches 99%, and the product quality reaches 99.99% .99.9% of the products are of superior grade (the light transmission rate reaches the polyester grade). The current technical specifications are as below:
The recovery rate of EG: 98%;
the product quality: 99.9%;
the products reaches superior grade: 90% .



3、The biggest advantage of this process is: energy saving!

For EG distillation system the steam consumption is ≤ 2 MTs of steam per MT EG.
At present, in Xinjiang an enterprise with 200,000 MTs EG distillation ,the energy consumption is 4-4.5 MTs steam / MT EG,
In Inner Mongolia, for an enterprise 300,000 tons EG distillation, the energy consumption is 4.5 MTs of steam / MT EG. For a 500,000 Mts system, the steam energy consumption can be saved by 0.15-0.2 billion yuan per year.
4、The impurities were studied deeply which affect the light transmission of the products. Now we master the separation and the entire technology. By using alkylation, transesterification, internal hydrolysis, acetal and other reactions, the esters and aldehydes that affect the UV light transmittance is converted to substances that is easily absorbed and removed and this increases the UN value of the EG product.
With this technology we can not only reduce the distillation energy consumption, but also improve the yield of excellent EG greatly.
5、The gas-liquid equilibrium of EG, butanediol and propylene glycol systems is measured accurately. The simulation and optimization of the EG distillation system is compared and corrected according to the experimental and production data ,so the data is reliable and the design is accurate; With the advanced technology of tower internals and the special stuffing for the EG distillation, it is very conducive for the enlargement of the coal EG devices. It does not need to design the magnification insurance coefficient or leave the margin. The technology is of low investment and stable operation. For the Hualu Hengsheng’s EG plant being built now, the EG distillation section is 500,000 Mts per set.
 
 
 

Name	Patent number / application number
A device for the synthesis of methyl nitrite	201521145219.7
A device for the synthesis of EG	201521145220.X
The catalyst and its preparation which is used in the preparation of ethylene glycol from the hydrogenation of the dimethyl oxalate	201510938746.1
the catalyst and its preparation and usage which is used in the preparation of dimethyl oxalate from CO	201510946659.0
The method and the device for the purification of acid gas and water in the outlet gas of esterification.

   In 2009 we established the engineering technology research center with Ningbo Institute of Industrial Technology (CNITECH), Chinese Academy of Sciences (CAS). Our core team consists of 16 scientists (7doctors and 9 masters) including Dr. Yu-Qiao Xiang and Dr. Hong-Feng Yin.

Fourth, economic performance indicators (such as 320,000 MTs / year ethylene glycol scale)
The raw materials are CO and H₂, and the devices include the ethylene glycol unit,the storage and transportation unit. the price of CO, H₂ is 0.91 yuan / Nm³ (VAT inclusive); The price of ethylene glycol is 5700 yuan / MT ((VAT inclusive).

First	Project Name	Unit	Quantity	Remarks
one	Total investment of the project	thousand yuan	131562
1	The construction investment	thousand yuan	119126
2	The interest during construction period	thousand yuan	5560
3	The current capital	thousand yuan	6876
	Among them: initial（start-up）working capital	thousand yuan	2063
Second	The Cost and Benefit
1	The average of annual turnover	thousand yuan	195107
2	Total annual cost	thousand yuan	111946
3	Total annual Profit	thousand yuan	53447
4	Unit complete cost	thousand yuan/Mt EG	35220	VAT inclusive
Third	Financial Evaluation Index	%
1	Total rate of return on investment(ROI)	%	41.98
2	Rate of return on common stock holders' equity(ROE)	%	101.56
3	Financial internal rate of return(FIRR)	%	38.20	before income tax
4	Financial internal rate of return(FIRR)	%	31.28	after income tax
5	Financial Net Present Value（IC=11%）FNPV	thousand yuan	2346320	before income tax
6	Financial net present value（IC=11%）FNPV	thousand yuan	1624770	after income tax
7	Payback period	year	5.60	before income tax
8	Payback period	year	6.42	after income tax
9	Breakeven point	%	29.87%

In March 2015 the technical transformation Hualu Hengsheng ’s ethylene glycol plant was completed and put into operation, the catalyst of hydrogenation and carbonylation were all replaced by our products. The quality met the national polyester standards. More than 95% of product are superior grade. Now the products have entered the polyester field successfully.


The production cost of Hualu Hengsheng’s ethylene glycol is 3190.54 yuan/MT and the full cost is 3517 yuan/MT. The average market price is 4600 yuan / MT, then the unit profit reaches 1083 yuan/MT. According to the current price of steel and building materials, if we build a new 200,000 tons / year of ethylene glycol plant the investment is about 700 million. If it produces with full capacity the pre-tax payback period is only five years.