n-Pentane and isopentane are two isomers of pentane, a hydrocarbon with five carbon atoms and 12 hydrogen atoms. They have the same molecular formula, C5H12, but different structures. n-Pentane has a straight chain of five carbon atoms, while isopentane has a branched chain with four carbon atoms in a row and one carbon atom attached to the second carbon atom. The difference in structure affects their physical properties, such as boiling point. The boiling point of a substance is the temperature at which it changes from liquid to gas. In this report, we will compare the boiling points of n-pentane and isopentane and explain the factors that determine them.

Results and Discussion

The data shows that the boiling point of n-pentane is higher than that of isopentane. According to the web search results, the boiling point of n-pentane is 36.1°C, while the boiling point of isopentane is 27.9°C. This means that n-pentane requires more energy to vaporize than isopentane. The reason for this difference is the intermolecular forces between the molecules. Intermolecular forces are the attractions between molecules that hold them together in a liquid or a solid. The stronger the intermolecular forces, the higher the boiling point.

The main type of intermolecular force in n-pentane and isopentane is the van der Waals force, which is a weak attraction between the temporary dipoles of the molecules. A dipole is a separation of positive and negative charges in a molecule. A temporary dipole is a dipole that forms when the electrons in a molecule are unevenly distributed at a certain moment. The temporary dipole of one molecule can induce a temporary dipole in another molecule, creating a van der Waals force between them.

The strength of the van der Waals force depends on the size and shape of the molecules. The larger and more elongated the molecule, the stronger the van der Waals force. This is because a larger and more elongated molecule has more surface area for the temporary dipoles to interact. n-Pentane has a larger and more elongated molecule than isopentane, as shown in the figure below.

![n-pentane and isopentane structures]

Therefore, n-pentane has stronger van der Waals forces than isopentane, and thus a higher boiling point.

Conclusion and Recommendations

In conclusion, we have analyzed the boiling points of n-pentane and isopentane and found that n-pentane has a higher boiling point than isopentane due to the stronger van der Waals forces between its molecules. This analysis demonstrates the importance of molecular structure in determining the physical properties of substances. We recommend that you use this knowledge to understand the behavior of other hydrocarbons and their isomers.

The blowing agent used since EPS Foam was first introduced in 1952 by BASF is Pentane gas which, does not contain any chlorine atoms as CFC’s. PSP Foam in the beginning used CFC’s as blowing agent. In the past two decades CFC’s are gradually phased out from plastics and refrigerator industries.

It is contemplated that various blowing agents may be used in the present invention, including physical blowing agents such as hydrocarbons. The preferred physical blowing agents for this invention are organic chemical compounds that have boiling points less than about 37° C. These organic compounds include, but are not limited to, fully hydrogenated hydrocarbons and partially fluorinated hydrocarbons that are considered to be flammable. Flammable as defined herein generally includes those materials having flashpoints less than about 37.8° C.

The preferred fully hydrogenated hydrocarbon blowing agents include the initial members of the alkane series of hydrocarbons that contain up to five carbon atoms and which are not regulated by governmental agencies as being specifically toxic to human or plant life under normal exposure. These fully hydrogenated blowing agents include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane and blends thereof.

The most preferred fully hydrogenated hydrocarbon blowing agents are C₂ to C₄ compounds and blends thereof An example of a preferred blend is a blend of approximately 67 weight percent n-butane and approximately 33 weight percent isobutane, which is commonly referred to in the industry as an A21 butane blend. This blend may be added at a rate of from about 1 to about 20 weight percent of the total extruder flow rate, and preferably added at a rate of from about 3 to about 20 weight percent of the total extruder flow rate.

It is contemplated that auxiliary blowing agents may be used in the present invention in amounts less than about 40 weight percent of the total blowing agent. The preferred auxiliary blowing agent are partially fluorinated hydrocarbon blowing agents that have molecules containing up to three carbon atoms without any other halogen atoms, and those considered flammable. For example, this includes 1,1-difluoroethane (HFC-152a), and 1,1,1-trifluoroethane (HFC-143a), with the most preferred auxiliary blowing agent being HFC-152a. It is also contemplated that 1-1-chlorofluoroethane (HFC-142b) and 1-1-dichloro-2-fluoroethane (HFC-141b) may be added as auxiliary blowing agents for non-regulated insulation applications.

In addition, water may optionally be added at a low concentration level as an auxiliary blowing agent. The water quality should be at least adequate for human consumption. Water containing a high level of dissolved ions may cause excessive nucleation, so therefore deionized water is preferred. The preferred rate for water addition is from about 0.05 to about 0.5 parts water to 100 parts of the polymeric composition (0.05 to 0.5 phr). The most preferred rate of adding water is from about 0.2 to about 0.3 phr.

What is EPS

Polystyrene is one of the most widely used kinds of plastic. It is a polymer made from the monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is a thermoplastic substance, it melts if heated and becomes solid again when cool.

Polystyrene is most commonly found in three forms. Rigid Polystyrene (PS), Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS).

Rigid polystyrene has many applications including disposable cutlery, cd cases, video/casette casings, components for plastic model toys as well as some margarine and yoghurt containers.  Extruded polystyrene foam has good insulating properties making it important as a non-structural construction material.  XPS is sold under the trademark Styrofoam by Dow Chemical, however this term is often used informally for other foamed polystyrene products.

How to produce foam?

Expandable Polystyrene / EPS:

This is PS Foam that uses Pentane gas (C5H12) as the blowing agent. During the material production process called “Polymerisation” the polystyrene resin granules impregnated with the blowing agent. EPS production processes begin in the pre-expansion process where the EPS bead will expand by the heat of steam usually 50 times in volume. The next step in the process is moulding process where expanded foam bead will be heated again with steam then they expand further until they fuse together, forming as foam products.

There are mainly 2 types of EPS moulding machines;

• Shape moulding machine that produce various shapes of foam products according to the molds such as icebox, helmet and packaging foam.
• Block moulding machine that produce block foam and sheet foam Expanded EPS foam bead contains 98% air per volume, only 2% is plastic. This make EPS foam very light weight, has low thermal conductivity because air is the best insulation, high compressive strength and excellent shock absorption. These properties make EPS to be ideal material for packaging and construction.

Polystyrene Paper (PSP):

This is a PS Foam which is produced by extruding process as another plastic. Production process start when put polystyrene resin pellets into the extruder that heated by electric. Foaming process occur at the end of extruder where the blowing agent, butane (C4H10) gas react with the melt plastic then become foam. The melted polystyrene foam is then extended as sheet then rolled as paper roll, that is why it is commonly known as “Polystyrene Paper”. The polystyrene foam sheet or polystyrene paper can be produced as many shape according to the mould by thermal forming process such as food tray, cups, bow, and food box.

Both EPS and PSP contain 95 -98 % air another 2-5% is polystyrene which is pure hydrocarbon. CFC’s is Chlorofluorocarbons which is totally different in its chemical structure from polystyrene. CFC’s has very low blowing point and uneasy to be maintained in EPS beads. Therefore, EPS Foam never use CFC’s at any stage of its production. The blowing agent used since EPS Foam was first introduced in 1952 by BASF  is Pentane gas which, does not contain any chlorine atoms as CFC’s. PSP Foam in the beginning used CFC’s as blowing agent. In the past two decades CFC’s are gradually phased out from plastics and refrigerator industries. PSP moulders in Thailand already use Butane (C4H10) as the blowing agent since the last 15 years. Butane gas is the gas that we use at home for cooking. The blowing agents that use in producing PS Foam are Pentane and Butane, which are pure hydrocarbon as polystyrene. They belong to the same chemical family, the paraffin series as methane, ethane, and propane gas.

How to manage the EPS foam waste

Apart from recycling by melting and compacting, there are many ways to manage the EPS waste as the followings:

• Crush in to small particle and mix with soil. Foam waste will improve ventilation in the soil, organic substances in the soil will become easier the humus.
• Mixing the crushed bead with cement to reduce the weight and increase insulation properties.
• Combustion at 1000 C with sufficient air supplies in to generate heat. Burning EPS require no any additional fuel, in fact EPS can replace the fuel normally required for combustion, l kg of EPS saves 1 kg = 1.2 – 1.4 Litre of fuel oil.

The Recycling of PS:

Since both EPS and PSP Foam are made of Polystyrene, which is thermoplastic, so that it will become again a polystyrene plastic when recycled. AMEPS members recycle both EPS and PSP Foam by first crushing into small particle then melting or compacting it. Melting can be done by heated roller, disk or screw extruders, where the regrind scraps is heated usually by electrical power for some time above the melting temperature. Compacting can be done by rotary compactors where pressure and frictional force create heat below melting temperature to soften the regrind scraps for only few seconds. This method also called “agglomeration”.PS pallet from recycled foam will be produced in various kinds of plastic products e.g. video and tape cassette and ruler. The other way to reuse EPS Foam is to mix the regrind beads with the new expanded bead for re-production in moulding process.

At present, domestic pentane production technology mainly comes from Tianjin University and Beijing Research Institute of chemical industry. The main raw materials are light hydrocarbon in oil field, topping oil in crude oil pretreatment unit, light naphtha in hydrogenation unit, mixed hydrocarbon after reforming and hydrogenation, C5 in refinery gas separation unit and C5 fraction from cracking by-product of ethylene unit. It can also be obtained by separation and refining of mixed C5 after C5 etherification, or by hydrogenation of cyclopentadiene.
The C5 fraction obtained from straight run gasoline, natural gas condensate, hydrocracking tail oil and reforming gasoline is mainly obtained from pentane separation column and isopentane column by high-efficiency distillation. The main process flow is as follows (taking natural gas condensate as an example): it is heated to 55 ℃ in the preheater before entering the debutanizer. The operating pressure of the debutanizer is 0.34 MPa. Propane and butane fraction are taken out from the top of the tower (the top temperature is 48 ℃), part of the top condensate is used as reflux liquid, and the excess condensate is heated to 76 ℃ through the heat exchanger before entering the depropanizer. The operating pressure of depropanizer is 2 MPa. Propane is removed from the top of depropanizer (the top temperature is 50 ℃) and butane is removed from the bottom of depropanizer. The gasoline from the debutanizer kettle enters the depentanizer. The number of depentanizer plates is 30, the operating pressure is 2.2 MPa, the reflux ratio is 1.5, and the overhead fraction is condensed and then enters the isopentane separator. The number of plates of isopentane separator is 60-80, the top temperature is 58 ℃, the reflux ratio is 10.0, and the operating pressure is 0.2 MPa. The purity of the distillate from the top of the tower is 95% isopentane, and the distillate from the bottom of the tower is 90% n-pentane.

Pentane and other products can be separated from mixed C5 separated from FCC LPG and ethylene units. The main process is hydrogenation under the condition of new Ziegler type catalyst. The reaction temperature is 60-80 ℃, and the pressure is 0.8-1.0 MPa. After hydrogenation, C5 can be separated into isopentane, n-pentane and cyclopentane by distillation

Solvent carrier for linear low density polyethylene (LLDPE)

N-pentane is mainly used as carrier solvent for LLDPE. China’s LLDPE production began in the 1960s. By the end of 2000, with the rapid development of China’s light industry and plastic industry, the consumption of LLDPE has increased rapidly. Many enterprises have built more than 10 sets of large-scale and technologically advanced production units by introducing foreign technology and equipment, and the production capacity has reached 1.05 MT / A. According to the process requirements of products, the proportion of n-pentane per ton of LLDPE is generally 0.3%. Therefore, the annual consumption of n-pentane in LLDPE field is about 3 KT.

Puffing agent for cut tobacco

Isopentane was used as solvent for tobacco expansion. The main function of tobacco puffing is to reduce the consumption of tobacco leaves, reduce the tar and nicotine content of cigarettes, and improve the quality of tobacco leaves. The puffing technology can save 2.5-3.0 kg of cut tobacco per box of cigarettes (about 50 kg cut tobacco), and effectively improve the quality of cut tobacco. Imperial Tobacco has developed IMPEX tobacco expansion technology and equipment with isopentane as solvent to replace CFC (Freon) tobacco expansion system. Since 1995, IMPEX system has been used to expand cut tobacco for cigar. Compared with CO2 expansion system, this system has higher expansion rate and higher filling capacity of tobacco.
Among 179 cigarette factories in China, 57 use CFC-11 expansion process, and the consumption of CFC-11 in 1998 was 1 003 t. At present, some large-scale tobacco enterprises in China use liquid CO2 to expand instead of CFC-11. According to the substitution situation of foreign tobacco industry, isopentane as expansion agent has a certain market prospect in tobacco expansion technology.

Pentane
CAS Number 109-66-0.
Linear Formula CH3(CH2)3CH3
Molecular Weight 72.15.
Beilstein/REAXYS Number 969132.
EC Number 203-692-4.
MDL number MFCD00009498.
PubChem Substance ID 57648039.
NACRES NA.21.

Pentane is an organic compound with the formula C5H12 — an alkane with five carbon atoms. The boiling points of the pentane isomers range from about 9 to 36 °C. It has two isomers n-Pentane and iso-Pentane and a special variant as cyclopentane.

Due to its low boiling range and fast evaporation, Junyuan Petroleum Group’s pentanes can be primarily used as environmental friendly blowing agents in the production of EPS and PUR industry.

In addition, pentanes have a wide range of application, act as excellent refrigerant in geothermal power stations, solvent in catalytic processes, resins, propellant in aerosols and it is essential for gasoline production.

Our product represents higher quality than pentane produced by oil refineries. Its minimum 95% purity and low contaminations make our product particular (with special attention to the sulfur content).

Junyuan Petroleum Group offers you iso- and normal- and a wide selection of pentane blends designated to fulfil the requirements of insulation, chemical and fuel industries. We produce the iso- and normal-pentane separately, so we can blend any tailor-made mixture upon your request.

You can download a sample of our specifications:

n-Pentane – Iso-pentane
20/80 Iso/Normal-Pentane Blend
30/70 Normal/Iso-pentane blend

Junyuan Petroleum Group represents as a reliable supplier of the most important market players in the EPS industry in China and around the world for more than 11 years.

We apply high standards and possess the latest ISO certificates in addition to our continuous, computerized production control.

Based on our assets Junyuan Petroleum Group provides you high-level logistic service at our storage park, loading stations and transportation while respecting our high HSE standards. We can offer you drum and ISO Tank deliveries or loadings at our site and our main aim is to supply you On Time, In Full.

Junyuan Petroleum Group’s key goal is to provide first class service for the customers, so we dedicated a sales expert and a whole team will work on your satisfaction.