Table of Contents
Chemical Make up:
Phenol is part of a family of organic compounds distinguished by a hydroxyl (-OH) group attached to a carbon atom that is part of an aromatic ring. The term phenol serves as a generic name for the entire family but it is also the specific name for its simplest member, monohydroxybenzene (C6H5OH) also known as benzenol, or carbolic acid. In a way Phenols are similar to alcohols but form stronger hydrogen bonds therefore are more soluble in water and have higher boiling points than alcohols.
Molecular weight: 94.113g/mol
Melting point: 40.91oC
Flash Point: 85oC (open cup) 79oC (closed cup)
Boiling Point: 182oC
Water Solubility: 82800mg/L (@25oC)
Relative Vapour Density (air=1) :3.2
Colour: Colourless to white crystals can be pink or red when impurities are present.
Odour: Sickeningly sweet and acrid tarry odour
Taste: Sharp and burning
Heat of combustion: 3053.5 kJ/mol
Heat of vaporization: 57.82 kJ/mol @25oC
Phenol is an intermediate compound which finds its important use as the raw material for manufacturing synthetic resins, synthetic fiber, agricultural chemicals, surface active agents, etc. and today the world’s annual consumption of phenol has reached approximately 3 million tons.
This compound was first isolated from coal tar by F.F. Runge in 1834 and with the development of organic chemical industry in the latter half of 19 th century, the demand for phenol increased appreciably, which in turn prompted various studies to develop processes for synthetic phenol. The first of such processes was the Sulfonation Process which is still in use by some plants operating on a small scale.
During World Wars I and II, phenol was utilized in large quantities as the raw material for producing military explosives. It was during this period that the Sulfonation Process was further improved and such other processes as Chlorination Process and Raschig Process were first commercialized.
With the growth of petrochemical industry after World War II, Cumene process was developed, which now accounts for approximately 80% of the world’s phenol production.
Thereafter, phenol syntheses were attempted by such methods as toluene oxidation via benzoic acid and oxidation of cyclohexane, which, however, have been subsequently abandoned.
Either of these methods is more or less complicated and requires considerable utility consumption. Although it is theoretically possible to obtain phenol by oxidation of benzene which is in fact considered the simplest form of phenol synthesis, but none of these methods have been found economically justifiable. It is indeed hoped that a much more simple method be developed in view of the importance of phenol as an important basic chemical.
More than 99% of phenol produced worldwide is from synthetic processes. The first synthetic phenol was produced by sulfonation of benzene and hydrolysis of the sulfonate. In 1924, Dow Chemical started to commercialize synthetic phenol based on the direct chlorination of benzene to chlorobenzene, but later a different variation of this process was developed based on the oxychlorination of benzene with hydrochloric acid (HCl) to form chlorobenzene. In the early 1960s Scientific Design developed a non-chlorination route to phenol based on the production of cyclohexane intermediate and Schenectady Chemical Company attempt to commercialize a direct air oxidation route for benzene-to-phenol, based on the vapor phase oxidation of benzene.Since the mid-20th century, patents pertaining to phenol production have primarily focused on improvements to the current process rather than an alternative. One example is a European patent filed by Mitsui Petrochemical LTD in 1989. The patent application proposed a method to reduce the acetone by product through the integration of a recycle loop. The recycle stream, containing acetone separated from phenol, is hydrogenated to isopropanol, then returned to the reactor for benzene alkylation. This patent would reduce the operating cost, as less isopropanol would be needed to achieve similar yields.
- EP0371738A2, Mitsui Petrochemical Industries, November 1989
Another example is a patent filed in 2003 to increase the efficiency of phenol separation from a cumene mixture. The patent was intended to improve upon the downstream separation of a variation of the Hock process that increases phenol yield while decreasing operational and utility costs.
The demand for Phenol is primarily driven by the plastic industry. The major use of Phenol accounting for between 40-60% of annual production is the manufacturing of bisphenol-A, a key precursor to polycarbonates and epoxide resins .
Figure 1. World Phenol demand by application 2015. Image Credit: American Chemical Society
Bisphenol-A (BPA) 40-60%
Bisphenol-A is manufactured by condensation of phenol with Acetone and is used in the synthesis of plastics. BPA based plastic is clear and tough and is used in a wide variety of common consumer goods such as plastic bottles, sports equipment, Cd’s and DVD’s. 
In 2015 it’s estimated that 4 million tonnes of BPA chemical were produced for the manufacturing of plastics making it one of the highest volume of chemicals produced worldwide.
However due to recent publications describing BPA as a possible endocrine disruptor  there have been restrictions placed on its use in a variety of goods such as drinking bottles for infants/children, children’s toys , etc.  by the European Union.
Phenolic Resins or Phenol formaldehyde resins (PF)
Phenolic resins are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde .
As a raw material for Bakelite, phenolic resins became the first commercial synthetic plastics in 1909. And was used for a huge variety of applications from circuit boards to toys and jewellery.
In the current market the largest use for phenolic resins is the creation of phenolic laminates such as exterior plywood and paper composite panels.
Phenol was once widely used as an antiseptic  , while this application has been discontinued phenol is still found in medicinal applications such as oral analgesics ( Chloraseptic spray) in treatment of sore throats. Phenol is also used as a preservative in some vaccines.
1.1.1 The Phenol Market
The phenol market is growing stronger every year, in fact close to 12 million tonnes of phenol was produced in 2016  making the global phenol market size worth USD 11.75 billion that year . This is only the start of the markets growth, the global phenol demand rate is growing 4.5% per annum, while its production is growing at 4% per annum . The market is growing, and it is predicted that by 2025 the global phenol market will be worth an estimated USD 31.73 billion .
1.1.2 Raw Materials Market
From the research of the processes that exist in the world the main raw materials that are mainly used for the production of phenol are benzene, propene and cumene. Benzene is a chemical mostly produced as a by-product or in oil refineries. Benzene is used as a building block for many different chemicals but the largest being ethylbenzene and cumene. In 2016 these two chemicals accounted for nearly 70% of the world consumption of benzene . In terms of production Northeast Asia, mainly China accounted for near half the world production of benzene in 2016 . When looking at India, there is more benzene being produced than needed in the country and exports around 600,000 tonnes a year, which could be something that can be taken advantage of in our production .
Fig 1. Prices of benzene averaging 700-900 USD/Ton over the last year. 
The other key material needed for phenol production is propene. Propene is the second most produced petrochemical derivative after ethylene, propylene has many uses and is key in the production of different sealants and insulators . The compound annual growth rate is expected to grow by 6% for propylene in the coming years . Northeast Asia is the biggest consumer of propene accounting for close to 40% of the world consumption in 2016 . For production Asia are also leading producing close to 30 million tonnes a year .
Fig 2. Prices for propene around 800-1000 USD/Ton 
When benzene and propene are combined in an industrial level, they produce a chemical called cumene. In 2016 the cumene market size was valued at 18.8 billion . Cumene is the main chemical required for the production of phenol in today’s industry and in 2016 Phenol made over 61.4% of the total market revenue . In geographical terms, Asia Pacific mainly China, India and Japan made up 47.8% of the market in 2016 and is set to grow at a compound annual growth rate of 4.3% till 2025 .
Fig 3. Prices for cumene averaging in and around 1,100 USD/Ton .
When comparing wheatear it would be more beneficial to use both propene and benzene as your raw materials and produce cumene on site or to just buy in cumene, the research showed that buying cumene is a cheaper opinion saving the plant between 600-800 dollars for every tonne, not taking into account the cost of having to make the cumene in different reactors. However it may be of interest to watch the market analysis as cumene process are steadily rising every year and in 5-10 years it may be costing the company more to buy the cumene than to make it. When it comes to location there is plenty of all cumene, benzene and propene available in Asia-pacific, which more than likely will be the location of our plant, therefore there should be no issue sourcing any of the raw materials.
1.1.2 Product consumptions
As we have shown in the uses of phenol in this literature review, phenol is a very useful chemical and the demand for the chemical is continuing to grow around the world. The chemicals growing market is mainly due to the demand for its derivatives, one of which is epoxy resins a key component in the production of wind turbines, and as the world becomes more environmentally friendly more wind turbines are needed boasting the phenol market. The largest market share for the uses of phenol was polycarbonates which is predicted to maintain the largest share in years to come . If we break this down to end products, Bisphenol accounted for just under half of the market.
Fig 4. Breakdown of the end products consumption of phenol in 2015. 
Geographically phenol consumption is split into Asia-Pacific, Europe, North America and the Rest of the World. Asia Pacific dominated the phenol market and it enjoyed a 42.4% revenue share in 2016  and is expanding quicker than the rest of the world. The large market share enjoyed by the Asia Pacific is mainly due to China. China is the largest producer and consumer of phenol in the world. Western Europe and North America are also seeing gradual growth in the phenol market but are growing at a much slower pace than the Asia Pacific phenol machine. Western Europe and North America has been predicted to maintain the slow growth displayed by them for the coming years while Asia Pacific continues to grow and flourish.
Fig 5. Breakdown of the world consumption of phenol in 2017 
However, even though China is the largest producer of phenol in the world it still needs to import the chemical to meet the needs of consumption within the country. The rate at which China is importing the chemical has declined in the recent years however, as in 2013 China imported 365,000 tonnes of phenol which was a 39% decrease from 2012 . When considering the phenol market China is a key player which needs to be considered and talked about especially when considering the best location for a phenol production plant. China has also implemented lower operating cost and is becoming the strongest petrochemical production in the world.
188.8.131.52 The Gap in the Indian market.
Apart from China, Western Europe and the United states which are known as the largest consumers but when looking at world consumption and the phenol market there is one other country where the phenol market is growing and in years to come may be a very important factor in the world phenol market and there is India. A recent report published by the Indian government highlighted the demand-supply gap which excises in India, the report stated that in 2016 there was a market gap of 238,000 for Phenol and 202,000 for Acetone, the report also stated that this market gap will increase to 411,000 for Phenol and 362,000 for Acetone by 2020 .
Fig 6. The Demand-Supply Gap in India 
Ineos are the leading company in Phenol production, they produce up to 4 million tonnes a year and all their plants are located in Belgium, Germany and the US. The Ineos plant in Antwerp, Belgium is the largest phenol production plant in the world and produces 680,000 tonnes a year . Other major players in the phenol production industry are Mitsubishi Corporation, Shell, PTT Phenol and Aditya Birla Chemicals. All of which have plants spread across the Asia Pacific continent mainly in China, Thialand, and Japan. Some of the plants are located in India however there is still less competition to worry about in India with none of these having a large grasp on the Indian market.
1.1.4 Plant Size
As stated the largest phenol production plant in the world produces 680,000 tonnes a year, this is a very large plant and there are very few phenol production plants in the world that come close to that size. The average size of phenol production plants across Asia Pacific is between 100,000 tonnes to 200,000 tonnes. The research also stated that a phenol plant producing between 100,000-200,000 tonnes a year will pay for itself in 4.5 years from production start date in India . Therefore to survive in the market and supply the growing demand for the phenol in Asia Pacific, especially in India we have drawn up that we will be able to make profit and run an efficient working plant making up to 200,000-250,000 located in India.
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The sulphonation process was first used by the German chemical company BASF in 1899. The process consisted of first reacting benzene with sulphonic acid at around 150-170 degrees which would produce benzene sulponic acid. From this the product is neutralized using sodium sulphate and then fused with sodium hydroxide. This leaves us with sodium phenoxide. This sodium penoxide is reacted again with sulphuric acid and we will be left with crude phenol and sodium sulphate. 
Once we have obtained the crude phenol and separated it from the sodium sulphate we must use distillation towers to purify our phenol to achieve the cleanest product. You can achieve a percentage yield of around 80-90% , with research showing on average it is close to 88% .
Fig 1. Flowsheet for the benzene sulphonation process. 
This process was used right up to the 1960s, but it had one major flaw and that was the poor atom economy. The atom economy is the ratio of the molecular mass of the reactant to the molecular mass of the product . The research showed that on average the process had an atom economy of around 32.3%-36.7% which means around one third of the reactant mass left the process as the desired product phenol . The amount of waste that this processed produced was a major reason why it is no longer used in the industrial world today.
 Process, P. (2018) Phenol Production By Benzene Sulfonation Process [online], Enggyd.blogspot.com, available: http://enggyd.blogspot.com/2010/09/phenol-production-by-benzene.html [accessed 26 Sep 2018].
 Panov, G. (2010) “ChemInform Abstract: Advances in Oxidation Catalysis: Oxidation of Benzene to Phenol by Nitrous Oxide”, ChemInform, 32(26), no-no.
The chlorination process was developed by DOW Chemical in 1924. Mr. Dow became interested in producing phenol by a new process in 1922. The standard process at the time was the sulphonation of benzene followed by hydrolysis but Dow used the hydrolysis of bromobenzene. However with the high cost of bromine he wanted a new cheaper process. He hired a professor of chemistry William Hale and an assistant Edgar Britton who developed the Hale-Britton process for producing phenol.
There are three reactions involved in converting benzene to phenol using the chlorination route:
- Benzene + Cl2 → monochloro benzene
- Operating temperature: 85°C
- Catalyst: Fe or FeCl3 catalyst
- Benzyl chloride + NaOH → sodium benzoate
- NaOH is in aqueous media
- Operating conditions: 425°C and 350 atms
- Exothermic reaction
- Sodium benzoate + HCl (aq) → Phenol + NaCl (aq)
- Operating conditions: Nothing specific
Benzene based process developed by Mitsui Petrochemical. (not in commercial practice)
Mitsui Petrochemical patent for the production of phenol US patent number : US5180871A
Date filed: 19/01/1993
No commercial plant built ?
In 1993 Mitsui Petrochemicals Industries Ltd. filed a patent for the production of phenol via the steps listed below:
(a) Partial hydrogenation of benzene, followed by separating the reaction mixture into respective components of cyclohexene, cyclohexane and benzene
(b) oxidizing or hydrating thee separated cyclohexene into oxygen containing compounds of a cyclohexane
(c) dehydrogenating the oxygen containing compounds of a cyclohexane into a phenol
(d) dehydrogenating the cyclohexane separated in step (a) to convert the cyclohexane into benzene
(e) returning a part or all of the hydrogen formed in steps (c) & (d) back to step (a)
Biomass is the only renewable resource to be converted to liquid fuel and has been realised as one of the most sustainable replacements for petroleum based fuels. Phenol can be produced from lignocellulosic biomass by catalytic microwave pyrolysis. Microwave assisted pyrolysis induces heating within the core of the substance through a direct energy conversion which improves the products selectivity and energy efficiency, it also reduces the capital cost comparing with other conventional pyrolysis. Metal oxides and zeolites are the two types of catalysts that are most commonly used for catalytic MAP of lignocellulosic biomass. Lignocellulosic biomass is mainly composed of three polymers: cellulose, hemicellulose and lignin together with small amounts of other components, like acetyl groups, minerals and phenolic substituents. The major component of lignocellulosic biomass is cellulose.
The highest concentration of phenol produced by this method is 38.9%. This conversion rate was obtained at a temperature of 589K and a catalyst to biomass ratio of 3:1 with a retention time of 8 minutes.
- Biomass is a re newable source of energy.
- Lignocellulosic biomass is readily available and cheap.
- It is an environmentally friendly process.
- Low conversion to phenol of 38.9%
- High ratio of catalyst to biomass 3:1
- High cost of catalyst (the price of activated carbon is growing at a rate of 1.9% and is currently at $1440 per ton.)
Acetone is produced as a by-product of the cumene process along with phenol. While there is a growing demand for acetone expected to increase from 5.97 million tonnes per year in 2012 to 7.78 million tonnes per year by 2020 there is also an increase in production. In 2012 there was a surplus of 1.634 million tonnes of acetone produced worldwide. With the increasing production of phenol there is also an increase in the amount of acetone produced. With already having a surplus of acetone being produced it will become increasingly difficult to sell acetone.
Assignee: Council of Scientific and Industrial Research (CSIR New Delhi)
Employed Commercially: No
This novel process was patented by CSIR New Delhi in patent US8772552B2 which describes the process for generating phenol at high selectivity using benzene and air. This approach has many exciting benefits for the phenol industry including: fewer raw ingredients required, elimination of hazardous intermediate compounds (cumene hydroperoxide), relatively mild operating conditions, eliminated production of acetone, increased phenol selectivity. The irreversible reaction that takes place is shown below:
C6H6 + ½ O2 C6H5OH
There is no data available on processes used in industry as the production method is still in concept stage however from literature we can deduce that the benzene and air would be fed to a fixed bed reactor containing a catalyst made up of copper and chromium in a ratio of 1:2.5 and a temperature between 200-300 degrees. The pressure in the reactor is maintained by the air feed and will be between 2-4 MPa. The ideal time on stream would be between 2 and 18 hours. Following reaction, the resulting products are passed through a flash drum and distillation column to separate the unreacted benzene from the phenol.
- No by-products formed
- Reduced cost in raw materials
- High Phenol selectivity
- No hazardous intermediate compounds formed
- Single step reaction from benzene to phenol
- Catalyst used in relatively low amounts
- Limited information on process
- Not yet commercially applied
This process poses major improvements over the conventional cumene process as listed above. However it has yet to be employed industrially and the potential problems of such a plant have yet to be determined completely.
Application: A high-yield process to produce high purity phenol and acetone from cumene with optional byproduct recovery of alpha methyl styrene (AMS) and acetophenone (AP).
Description: Cumene is oxidized (1) with air at high efficiency (+95%) to produce cumene hydroperoxide (CHP), which is concentrated (2) and cleaved (3) under high yield condition (+99%) to phenol and acetone in presence of an acid catalysts. The catalysts is removed and cleavage mixture is fractionated to produce high purity products (4-8), suitable for all applications. AMS is hydrogenated to cumene and recycled to oxidation or optionally recovered as a pure by product. Phenol and acetone are purified. A small aqueous effluent pre-treated to allow efficient biotratment of plant wastewater. With AMS hydrogenation, 1.31 tons of cumene will produce 1 ton of phenol and 0.615 tons of acetone. This high yield process produces very high quality phenol and acetone products with very little heavy and light end byproduct. With over 40 years of continuous technological development, the Kellogg Brown & Root (KBR) phenol process features low cumene and energy consumption, coupled unsurpassed safety and environmental system.
Commercial plants: Thirty plants worldwide have been built or are now under construction with total phenol capacity of over 2.8 MMtpy. KBR has
Application: The Sunoco/UOP phenol process produces high quality phenol and acetone by liquid phase peroxidation of cumene.
Description: Key process steps:
Oxidation and concentration (1): Cumene is oxidized to cumene hydroperoxide (CHP). A small amount of dimethylphenylcarbinol (DMPC) is also formed, but low pressure and low temperature oxidation results in very high selectivity of CHP. CHP is then concentrated and unreacted cumene is recycled back to the oxidation section.
Decomposition and neutralization (2): CHP is decomposed to phenol and acetone, accomained by dehydration of DMPC to alphamethylstyrene (AMS), catayzed by mineral acid. This unique design achieves a very high selectivity to phenol, aceton and AMS without using recycle acetone. The high total yields from oxidation and decomposition combine to achieve 1.31 wt cumene/wt phenol without tar cracking. Decomposed catalyst is neutralized.
Phenol and acetone purification (3): phenol and acetone are separated and purified. A small amount of byproduct is rejected as heavy residue.
AMS hydrogenation or AMS refining: AMS is hydrogenated back to cumene and recycled to oxidation, or AMS is refined for sale.
Cumene peroxidation is the preferred rout to phenol, accounting for more than 90% of world production. The Sunoco/UOP phenol process feature low feedstock consumption (1.3 wt cumene/wt phenol) without tar cracking, avoiding the expense and impurities associated with tar cracking. High phenol and acetone product qualities are achieved through a combination of minimizing impurity formation and efficient purification techniques. Optimized design result in low investment cost along with low utility and chemical consumption for low variable cost of production. Design option for by-product alphamethstyrene (AMS) allow produces to select the best alternative for their market: hydrogenate AMS back to cumene. Or refine AMS for sale. No acetone recycle to the decomposition (cleavage) dection, simplified neutralization, and no tar cracking make the Sunoco/UOP phenol easier to operate.
Commercial Plant: the Sunoco/UOP phenol process is currently used in 11 plants worldwide having total phenol capacity of more than 1 million mtpy. Four addition process unit. With a total design capacity of 600,00 mtpy, are in design and construction
In 1992 Mitsui Petrochemical Industries Ltd. (Mitsui) began operating a 200,000 t/yr cumene based phenol plant at Chiba, Japan. Using a technology developed by Hiroshi Fukuhara and Fujihisa Matsunaga the plant incorporated the ability to recycle 120,000 t/yr of the by-product Acetone produced as part of this process. The Acetone is used to generate propylene which can be recycled as a feedstock for Phenol production. See figure X below detailing the reactions taking place.
Figure 2. Acetone recycling reactions. Image credit Nexant Chem Systems PERP report 2007
The acetone produced as a by-product of phenol production is hydrogenated in a fixed bed reactor using a Raney nickel catalyst at reaction temperature between 60-140 degrees. The hydrogen gas used in the reaction is added in a molar ration of 1/1 to 5/1 relative to the acetone reactant. (Liquid gas down flow method known as trickle bed preferred). The Isopropanol produced is dehydrated in a fixed bed reactor using a catalyst of ϒ-alumina or titanium oxide. The reaction temperature ranges from 260 to 350 degrees. The reaction vessel is preferably pressurized to maintain the reactants in the liquid phase. The recovered propylene can be purified using distillation. A simplified flow diagram of the process is shown in figure X
Figure 3. Simplified Process flow diagram of Mitsui Acetone recycling technology
According to Mitsui Chemicals selectivity of the process is quite high (98-99%). The main advantage of this process is the removal of acetone as a by-product. Through the Cumene process acetone is produced at a ratio of 6:10 ton acetone / ton phenol. The drawback of this is the difference in market for both products, with phenol in significantly more demand and acetone regularly overproduced. However lately the markets have been balanced with demand for acetone matching the output capacity .
- Capability to produce phenol without acetone.
- Reduced costs of raw materials due to onsite production of propylene.
- Increased initial capital expenditure.
- Increase in energy consumption.
While the mitsui process of acetone recycling is certainly interesting due to the removal of the problems of acetone sales and market some comment that the process is only superior to the conventional cumene process when there is almost zero demand for acetone or acetone derivatives. In the recent year the acetone market has stabilised and demand has been sufficient to allow for phenol plants using the cumene process to run at full capacity. Some companies have obtained licenses from Mitsui Petrochemical to employ the acetone recycling process but there have been no other plants constructed with this capability at present. Although there are drawbacks to this process with phenol experiencing higher CAGR in the Asia pacific market compared to acetone it is definitely a possibility to introduce facilities for acetone recycling in our plant.
In production of phenol from cumene develops through 5 process operation:
- Oxidation of cumene to CHP.
- Oxidation settling wash.
- CHP concentration.
- Cleavage of CHP to phenol and acetone.
- Fractionation and purification of cleavage mixture into acetone and phenol.
Each of the above steps involves many safety aspects mainly related to temperature (both the reactions are exothermic), explosive mixture cumene-air and CHP concentration. The following section is operating at low temperatures; CHP is concentrated to approximately 80-wt % and fed to the first of the two cleavage reactors.
The Cleavage Reactor and Its Modelling:
The CHP cleavage stage is an essential part of a phenol process. At the same time, it is one of the most complex process systems, and its potential for dangerous accidents and similar risks is ranked extremely high among other large capacity petrochemical processes.
The cleavage reaction takes places in a tubular loop reactor with two sections where heat exchange to remove the heat of reaction is provided. There are two inlet flowrates: one, in the upper part of the reactor, is constituted by cumene hydroperoxide, acetone and some by-products; in the other, fed at the bottom, also a small percentage of sulphuric acid, which acts as catalyst, is present. The pump at the reactor bottom allows recirculating up to one hundred times the total feed: the high acetone content dilutes the heat released by the exothermic reaction. The loop temperature sufficiently low (70-77°C) cleavage is conducted in a boiling mixture of acetone and phenol in order to operate with CHP dilute solutions and to remove heat reaction by evaporation of acetone (Caldi, 1999)
The main reaction of cumene hydroperoxide acid cleavage to phenol and acetone: