The effect of zinc stearate on thermal degradation of paraffin wax

Abstract

Petroleum waxes are complex mixtures of high molecular mass saturated hydrocarbons. These hydrocarbon mixtures mainly consist of n-, iso-, and cyclo-alkanes and traces of aromatic and hetero-analogous compounds in the range of C16-C65 [1,2]. They are mainly divided into two groups, macrocrystalline and microcrystalline waxes, according to their structural constituents. In refining industry, waxes are obtained as a by-product in lubricating oil manufacturing process. As paraffin waxes have excellent properties, such as water-repellency and lubricity they find a wide range of applications including paper and chipboard production, packaging materials, cosmetic and pharmaceutical industries, and plastic industries [2]. Apart from these, they are also used as a component of binder system in ceramic processing, metal powder molding and metal injection molding [3,4]. A technical grade paraffin wax was used as phase change material in deposition of solar energy due to its high latent heat of melting (i.e., 190 kJ kg -1 ) [5]. In most of its applications, thermal decomposition takes place during processing or sintering, such as ceramic or metal powder molding. Another use of paraffin wax is solid fuel for rocket systems. Recently, it has been studied as a high regression rate propellant. It is a candidate for rocket solid fuel, which is expected to replace the conventional rocket fuels, such as cryogenic combustible gases; polymethyl methacrylate (PMMA), high density polyethylene (HDPE), due to its low cost, reduced complexity and increased performance. It has been pointed out that paraffin wax regression rate is about 0.100 cm -1 , which is five times greater than the other solid hybrid fuels [6]. The thermal decomposition kinetics of RP-1 rocket propellant, which consists of paraffins, olefins and aromatics, was investigated between 375-500°C. Thermal decomposition kinetics of RP-1 was assumed to occur by first order reaction [7].Paraffin molecules having different chain length behave similarly towards most of the reactants under similar reaction conditions. When they are heated, they start to degrade into smaller chain lengths. The degradation of petroleum based material is assumed as first order reactions [8].The chain length can be decreased by high temperature treatment and solids having metal ions that act as catalysts. Paraffins in oxidizing media at high temperature undergo simultaneous pyrolysis and oxidation reactions. Pyrolysis of n-hexadecane, considered as paraffinic substance, was studied by Watanabe et al. at 500-550°C in a batch type closed reactor [9]. There were five elementary reaction groups in the pyrolysis of n-hexadecane; initiation, isomerization, b-scission, H-abstraction and termination. In this mechanism, n-alkanes were produced from H-abstraction and l-alkenes are formed via b-scission [9]. Polyethylene which is a polymeric paraffin was converted to liquid and wax products using zeolite with concentrations up to maximum mass by 50% [10]. Organometallic compounds are added to fuels in small qu...

Thermal analysis of the mixtures of paraffin with aluminum in wide temperature range

“…Obtained by the method of Kissinger activation energy of decomposition of paraffin E= 28.2 kcal/mol in agreement with the experimental data [7][8][9].…”

Study of the Viscosity and Thermal Characteristics of Polyolefins/Solvent Mixtures: Applications for Plastic Pyrolysis

“…For example, at 50% polymer in wax, the TGA curve showed a two-step weight change; the initial weight change corresponds to the wax volatilization and was ∼1/2 of the sample weight for all polymer/wax mixtures, and the second corresponds to the polymer decomposition in the sample. The thermal volatilization temperatures of the wax and of the polymers in the samples were similar to those observed in the literature. ,, …”

“…The thermal volatilization temperatures of the wax and of the polymers in the samples were similar to those observed in the literature. 31,49,52 As Figure 4 illustrates, in the DTG curve of LDPE/solvent and PP s /solvent, the peak temperatures for LDPE and PP s slightly decrease as the solvent percentage increases. The solvent peak in the LDPE/solvent and PP s /solvent mixtures showed similar behavior.…”

Catalytic Upgrading of Pyrolysis Wax Oil Obtained from Waxed Corrugated Cardboard Using Zeolite Y Catalyst

“…32 The minor and major peaks also depict the solid−solid phase and solid−liquid phase transition for the wax oil samples, respectively. 30,33 An increase in the pyrolysis temperature from 450 to 500 °C resulted in a slight increase in wax oil major melting peak temperature from 51.3 to 52.2 °C. The melting peak temperature decreased to 47.7 °C for WO550 yielding shorter-chain hydrocarbons, which have a lower melting point.…”