Thermal Cracking Research Articles

Kinetics study on supercritical water conversion of low-maturity shale for hydrogen-rich hydrocarbon gas generation

Supercritical water (SCW) has gained substantial interest for shale exploitation due to its high conversion efficiency. To quantify the generated gases and the mutual conversion of gases on reaction of shale in SCW, experiments were carried out in batch reactor at 400–600°C and residence time up to 480 min. The products are classified as residual solids, liquid intermediates and gases. Experimental results show that the generated gases are mainly C1, C2, C3 alkanes, H2 and CO2. The concentrations of C1 and C2 alkanes decrease with temperature and residence time but the other three are the opposite. A kinetic model of shale-intermediates-gases reaction is developed. This model can characterize the gas generation features of shale and SCW resulting from chemical reactions, and can quantitatively describe the mutual conversion between gases. The calculated results demonstrate well applicative for predicting gas concentration at various residence time within an acceptable deviation. The reaction process can be divided into three stages: pyrolysis of organic matter to generate intermediates, hydrolysis reaction and alkyl thermal cracking of intermediates to generate gases, mutual conversion between the generated gases. Reactions among gases involve methanation reaction, water-gas shift reaction and hydrocarbon gas decomposition. This study provides a potential kinetic model for the gas generation characteristics of reaction with shale and supercritical water.

A sustainable rapeseed oil-based bio-additive designed for hard asphalt binders: Performance, environmental, and economic assessment

The inherent properties of hard asphalt binder give it both mechanical and economic benefits, rendering it a naturally advantageous material for preventing permanent deformation at higher temperatures. However, its poor resistance to thermal and fatigue cracking limits its application in the paving industry. This study aimed to improve the low-temperature and fatigue performance of hard asphalt binders by using the newly developed vegetable oil-based sub-epoxidized rapeseed oil (SERO). Two SEROs with epoxidation degree of 49.1% and 98.1% were synthesized through an oxidation reaction, respectively. Subsequently, the microstructural characteristics of SEROs were examined by Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance tests. The anti-oxidative aging properties of SERO modified hard asphalt binders were investigated through the utilization of mass loss and aging index. Additionally, the comprehensive rheological properties of SERO modified hard asphalt binders were explored via dynamic shear rheometer and bending beam rheometer tests. Furthermore, the modification mechanism of SERO on hard asphalt binders was confirmed through the quantitative analysis using the FTIR test. The findings suggested the improvement in anti-volatilization and anti-oxidative aging performance of bio-modified hard asphalt binders, which was positively related to the epoxidation degree of SERO. A notable softening effect of SERO on the hard asphalt binders was observed, which enhanced their resistance to thermal and fatigue cracking at lower and intermediate temperatures. The epoxy groups within SERO engaged in ring-opening reactions, forming a new oxygen bridge bond by combining with the unsaturated double bond presented in the asphalt. Consequently, this process resulted in the formation of cross-linked structures within bio-modified hard asphalt binders, thereby enhancing the elasticity. Notably, this phenomenon was most conspicuous in the SERO-H modified 50# binder. Finally, the environmental and economic assessment of SERO modified hard asphalt binders were conducted by the techno-economic method and the emission factors technique. The data revealed that the production of one ton of SERO modified hard asphalt binders could reduce the production costs by about 30%, energy consumption and CO2 emissions by around 20% in contrast to styrene–butadiene–styrene block copolymer modified asphalt binders. Hence, the substantial economic and environmental advantages make SERO an attractive bio-renewable additive for sustainable pavements.

High-temperature thermal fatigue of Ni3Al-based single crystal alloy affected by wall thickness and peak temperature

Complex thin-walled structures are commonly employed in turbine components to improve cooling efficiency. However, thin-walled blades are prone to thermal fatigue failure due to the high thermal stress induced by frequent and abrupt temperature fluctuations during duty cycles. The thermal fatigue behavior of Ni3Al-based single crystal alloy with thin-walled structure during 25 °C ↔ 1000 °C/1100 °C was investigated by combining thermal fatigue tests and finite element simulation. The thermal fatigue demonstrated a significant thickness debit effect, with thermal fatigue property dropping as peak temperature and wall thickness increased. Wall thickness had a more pronounced effect than peak temperature. Visible slip traces were found on the wall thickness surface, and their density was positively correlated with wall thickness. Further investigation revealed that thermal fatigue is primarily driven by the octahedral slip system ({111}<110>), with significant contributions from (111)[101‾] and (1‾1‾1)[101]. Simulations of thermal stress distribution and J-integral at the crack tip during crack initiation and propagation stages indicated that wall thickness influences thermal fatigue properties by affecting thermal stress concentration at the notch and crack tip. Higher peak temperatures increased thermal stress and reduced yield strength, thus diminishing thermal fatigue performance. A thermal fatigue crack propagation prediction model was constructed incorporating Paris' law and the J-integral. The model revealed an unfavorable correlation between material Cj/ nj and both peak temperature/wall thickness, indicating that both factors adversely affect thermal fatigue resistance.

Photoelasticity-based stress field analysis of glass under 1064 nm laser irradiation

Laser-induced thermal cracking in glass cutting surpasses traditional methods. Understanding dynamic thermal stresses is crucial for exploring mechanisms and controlling trajectories. We developed a real-time stress measurement system using the photoelastic method. Scanning soda-lime glass with a 1064 nm laser at various speeds, we analyzed stress changes with a finite element model. Results revealed phase entanglement issues, resolved by phase unwrappling. Stress differences peaked at 105 MPa (2 mm/s) and 78 MPa (4 mm/s). 2 mm/s scanning led to wider, longerwrapp cracks than 4 mm/s due to higher stress levels. Simulation and experimental results agreed, enhancing stress analysis comprehensively.

Multi-pulse femtosecond laser ablation of SiC/SiC composites: Morphological evolution, oxidation mechanisms and component characterization

SiC fiber reinforced SiC matrix (SiosC/SiC) composites processed by femtosecond laser play a pivotal role in thermal protection systems. This paper reveals the ablation characteristics of multi-pulse femtosecond laser ablation of SiC/SiC composites, including morphological evolution, oxidation mechanisms and component characterization by heat accumulation simulation and advanced experimental analysis. The results show that the ablation depth induced by the heat accumulation effect is an exponential function of laser parameters. Morphological analysis and component characterization indicate that two types of ablation regions are formed, normal ablation region is an oxidized zone induced by passive oxidation mechanism, and central ablation region is a non-oxidized zone induced by active oxidation mechanism. The increase of single pulse energy and decrease of scanning speed enhance the driving force of chemical reactions, thus dramatically affecting the gas hole and graphite properties in the normal ablation region. Furthermore, the propagation path of thermal stress-induced cracks is determined which emerges from the center ablation region, extending through gas holes to the normal ablation region.

Fabrication of bimetallic-doped materials derived from two polymorphic Ni-Mo-based coordination polymers for enhanced dye removal and gaseous iodine capture

Two polymorphic Ni–Mo-based coordination polymers (CPs) based on the ligand N,N′-bis(4-pyridinecarboxamide)-1,2-cyclohexane (4-bpah) were created using hydrothermal synthesis. Each of these CPs (denoted as Ni–Mo-1 and Ni–Mo-2) has the similar main framework [Ni(4-bpah)2(Mo2O7)], but they each show different crystalline phases with different 2D grid windows. Moreover, the Ni–Mo-based CP-derived carbon-based composites (C–Ni–Mo-X-Y, X = 1 or 2 and Y = 400, 450, or 500) were prepared by thermal cracking and “low-temperature” calcination below 500 °C using two CPs as precursors. The results show that the Ni–Mo-based CP-derived carbon-based composites prepared at different temperatures exhibit irregular morphologies with different micron-sized or nano-sized loose structures and chemical compositions. Furthermore, the dye and gas iodine adsorption properties of the C–Ni–Mo-X-Y composites were investigated in detail.

Converting of Waste Crude Oil of East Baghdad Oil Field into Light Hydrocarbons Using Thermal Cracking Technology

East Baghdad oil field produces a lot of quantities of waste crude oil due to drilling and production processes activities. This waste is caused a negative impact on the environment and human health. In the present investigation, the collected waste crude oil of API= 13 was converted into light hydrocarbons via a thermal cracking reaction. The thermal cracking process was achieved in a batch reactor at temperatures ranging between 350-450°C in absence of oxygen. At each temperature, the reaction pressures varied between (1-6) kg/cm2. Moreover, a continuous stirring of the reaction mixture inside the reactor was continued during the course of the thermal cracking process at a velocity of 96 rpm. The best yield of produced liquid hydrocarbon, gases, and coke at optimum conditions was 77.56 wt.%, 9.3 wt.%, and 13.14 wt.%, respectively. Actually, this process regards cheap, and simple with a high rate of liquid hydrocarbon production as well as environmentally beneficial.

Influence of Elevated Temperatures on the Compressive Strength of Concrete Made with Different Types of Aggregate

Concrete, the backbone of modern infrastructure, exhibits varying mechanical behaviour that depends on its components, with aggregates playing a crucial role in its strength and durability. This study aimed to investigate the influence of elevated temperatures on the compressive strength of concrete made with different types of aggregate. A comprehensive evaluation of concrete mixes was conducted using quartz, crushed clay bricks, crushed andesite, expanded clay and expanded glass coarse aggregates. For each coarse aggregate type, concrete mixtures were made with the same amount of Portland cement, water-cement ratio, natural sand, and superplasticizer. The effective water-cement ratio and cement content were kept constant in each concrete mixture. The grading and maximum particle size were the same in all concrete mixtures. The results revealed that the type of aggregate has a significant impact on the compressive strength and thermal resistance of concrete, with andesite-containing concrete exhibiting the highest residual strength after heating up to 800 °C and clay brick-concrete displaying the highest strength under elevated temperatures up to 1000 °C. The study also found that the age of concrete affects its strength at elevated temperatures, as concrete in the early stages of hydration is more susceptible to thermal cracking than concrete that has had more time to cure. Generally, the compressive strength of normal-weight aggregates depends on the strength of the parent rock. But in the case of fire (elevated temperature), the cement paste matrix loses its strength, and the aggregates effects become more significant.

Mechanical Properties and Interfacial Characterization of Additive-Manufactured CuZrCr/CoCrMo Multi-Metals Fabricated by Powder Bed Fusion Using Pulsed Wave Laser.

In this study, CoCrMo cuboid samples were deposited on a CuZrCr substrate using laser powder bed fusion (L-PBF) technology to investigate the influence of process parameters and laser remelting strategies on the mechanical properties and interface characteristics of multi-metals. This study found that process parameters and laser scanning strategies had a significant influence on the mechanical properties and interface characteristics. Samples fabricated with an EV ≤ 20 J/mm3 showed little tensile ductility. As the volumetric energy density (EV) increased to a range between 40 J/mm3 and 100 J/mm3, the samples achieved the desired mechanical properties, with a strong interface combining the alloys. However, an excessive energy density could result in cracks due to thermal stress. Laser remelting significantly improved the interface properties, especially when the EV was below 40 J/mm3. Variances in the EV showed little influence on the hardness at the CuZrCr end, while the hardness at the interface and the CoCrMo end showed an increasing and decreasing trend with an increase in the EV, respectively. Interface characterization showed that when the EV was greater than 43 J/mm3, the main defects in the L-PBF CoCrMo samples were thermal cracks, which gradually changed to pores with a lack of fusion when the EV decreased. This study provides theoretical and technical support for the manufacturing of multi-metal parts using L-PBF technology.

Analysis of pore-fracture structure evolution and permeability in tar-rich coal under high-temperature pyrolysis using μCT technology

To study the internal evolution characteristics of tar-rich coal under high-temperature pyrolysis and improve pyrolysis efficiency, three-dimensional reconstruction and analysis of tar-rich coal from northern Shaanxi after high-temperature pyrolysis were conducted using μCT technology. The evolutionary development of pore and fracture structure at different temperatures and the relationship between pore-fractures and permeability was studied and discussed. The results show that when tar-rich coal from 300 to 600 °C, it mainly undergoes two stages: in the first stage, the internal substance structure of the coal mainly undergoes thermal cracking, forming large fracture bands; in the second stage, the coal undergoes intense pyrolysis reactions, resulting in primarily circular or elliptical large pore structures within the coal, with a reduction in the number of fractures. Furthermore, a strong exponential relationship is exhibited between the porosity and permeability of tar-rich coal, and a predictive equation is provided. When the temperature exceeds 500 °C, the coupled effect of pores and fractures contributes more than 20% to permeability, and its impact cannot be ignored.

Peridynamics thermomechanical coupling simulation of damage in engineered cementitious composite-concrete bonding specimens under high temperature

The current application of Peridynamics (PD) models in addressing thermally induced failures within Engineered Cementitious Composites (ECC) and concrete bonding specimens is relatively limited. This study introduces a novel semi-discrete PD model for ECC and a random heterogeneous PD model for concrete. These models are grounded in the microscopic constitutive relationships between ECC and concrete materials and incorporate the strain softening behavior of cement-based materials. The effectiveness of the interface model is evaluated through splitting tensile tests on ECC-concrete bonding specimens, employing a series model alongside PD surface effects for material interface correction. Considering the performance degradation of materials at elevated temperatures, a PD thermo-mechanical coupling model, which integrates PD thermal diffusion and motion equations, is proposed to analyze the failure of ECC and concrete under high thermal loads. The validity of both the thermo-mechanical coupling and concrete heterogeneity models is confirmed via thermal cracking tests on heated concrete columns subjected to drilling. Lastly, considering the dynamic response of fire, the Navier-Stokes equation are reformulated into a non-local form utilizing the Peridynamic differential operator (PDDO) to simulate fire environment. A thermo-fluid-mechanical coupling model is developed, and applied to analyze ECC and concrete bonding specimens’ failure behaviors under fire scenarios.

Kinetic modeling for upgrading of heavy crude oil via thermal cracking in porous media: SARA fractions and gas compositions

Pyrolysis is regarded as the primary reaction for heavy crude oil upgrading during ISC process, and gas compositions produced by this reaction is also gaining attention. It is critical to establish the kinetic model to predict all products. The kinetic of heavy oil upgrading was studied and all experiments were carried out in an autoclave at 350–450 °C, 0.5 MPa, and 1–10 h. An improved kinetic including SARA fractions, coke, and gas compositions was proposed be more detailed description of the reaction process. Smaller SSE and bigger coefficients of determination (>0.99) of parity plots suggested the accuracy of calculated parameters of the improved kinetic model. The sensitivity analysis results demonstrate that the obtained kinetic parameters represent the optimal values. Gas prediction, a neglected aspect in previous studies, was also addressed, further enhancing the model’s utility.

Investigating the synergistic anti-aging effects of Sasobit and recycled engine oil in styrene-butadiene rubber modified asphalt

During the preparation of asphalt mixtures, styrene-butadiene rubber (SBR) polymers are susceptible to thermal decomposition, which can significantly impair the binder’s low-temperature performance. This study explores the potential of combining warming agents with waste materials to enhance the low-temperature properties and aging resistance of the binder. Specifically, it examines the synergistic impact of Sasobit/recycled engine oil (Sasobit/REO) composites on the rheological and physical attributes of styrene-butadiene rubber asphalt binder (SBRAB). Utilizing fluorescence microscopy (FM), bending beam rheometer (BBR), and dynamic shear rheometer (DSR), the study assesses the aging resistance and modification mechanisms of Sasobit/REO on SBRAB. The findings indicate that the incorporation of Sasobit/REO composites more effectively reduces the mix preparation temperature than either component alone. The preparation of Sasobit/REO warm mix asphalt mixtures is feasible at temperatures 20°C lower than those required for traditional hot mixtures. These composites also enhance the performance of SBRAB at both high and low temperatures, counteracting the adverse effects associated with the individual use of Sasobit or REO. This reduced short-term aging temperature is beneficial in lessening the negative impact of high temperatures on SBRAB’s performance. Moreover, the addition of Sasobit/REO composites significantly improves the thermal cracking resistance of SBRAB mixtures. The study also demonstrates that Sasobit/REO enhances the short-term and long-term aging resistance of SBRAB, paving the way for the broader application of this novel warm mix additive in the asphalt industry.

Flow and heat transfer characteristics of hydrocarbon fuel in lightweight C/SiC regenerative cooling combustor

To meet the requirements of higher thermal protection ability and lower structural weight of regenerative cooling structures in advanced hypersonic vehicles, carbon-fiber-reinforced silicon carbide (C/SiC) composites with high permittable service temperatures and low densities are promising for application in thermal protection systems. In this study, four cylindrical regenerative cooling configurations applying C/SiC composites for a designated scramjet engine combustor are proposed, and the thermal protection performance under the influence of the cooling equivalence ratio (0.4∼1.0) and anisotropic thermal conductivity is studied. The results show that the C/SiC composites can significantly improve the heat resistance of the entire regenerative cooling structure owing to their relatively low thermal conductivity, which reduces the total heat flux transferred to the inner structure. The thermal protection ability can be maintained, whereas the coolant flow rate is reduced by 50%. C/SiC composites with higher thermal conductivities in the circumferential direction are beneficial for uniform temperature distribution. A flow distribution deterioration phenomenon caused by the thermal cracking of the coolant and the increasing flow resistance in the cooling channels can be observed under certain conditions, leading to a mass flow rate difference of 2.5 times among the cooling channels. Moreover, introducing C/SiC composites into the regenerative cooling structure design can significantly reduce the total structural weight by over 50% compared to traditional superalloys.

Volatile light hydrocarbons as thermal and alteration indicators in oil and gas fields

Volatile light hydrocarbons (VLH) are an essential component of reservoir petroleum fluids. Understanding of their origin and fate is crucial not only in exploration but increasingly also in petroleum engineering, as this greatly impacts fluid typing, proper mapping, recoverability and economic value. Due to their sensitivity to subsurface thermal stress and geological alteration processes, their proper characterisation holds promise to understanding the thermal conditions under which petroleum fluids were generated and subsequent fluid modifications during migration and within the reservoir. To study the behaviour of these hydrocarbons under different geological conditions we selected oil and gas fields from two giant conventional petroleum systems in the Arabian Peninsula collectively spanning the entire petroleum spectrum from heavy oil to dry and sour gas. In situ representative bottomhole or recombined pressure–volume–temperature (PVT) fluid composition data were constrained with molecular and stable carbon isotope geochemistry in key wells. Systematic covariance among the slope factor (SF) of propane to pentane and the isomer ratios of butane and pentane with reservoir engineering and geochemical variables in well-constrained black oil to gas condensate petroleum systems allowed the derivation of three formulas to calculate thermal maturity in terms of vitrinite reflectance equivalent from VLH fluid composition: (1) %VRe(SF) = 0.38 SF + 0.41, (2) %VRe(i4) = 1.70 (iC4/nC4) + 0.61, and (3) %VRe(i5) = 0.89 (iC5/nC5) + 0.56. The slope factor, iC4/nC4, and iC5/nC5 ratios all increase monotonically with the thermal evolution of unaltered fluids, allowing for effective application of their derived %VRe formulas across the entire unaltered fluid spectrum, from heavy oil to dry gas. Deviations from indigenous-fluid trends do occur for fluids altered by phase separation, biodegradation, thermal cracking, and thermochemical sulfate reduction (TSR), but corrections can be made to minimize uncertainty in assessing true thermal maturity of altered fluids while respecting other reservoir fluid properties such as gas-to-oil ratio (GOR) and saturation pressure relationships. For instance, although a single charge that has been phase fractionated yields fluids with variable GORs, saturation pressures and slope factors, their butane and pentane isomer ratios remain reflective of the original fluid maturity. In contrast, biodegradation-induced overestimation of maturity based on the isomer ratios of butane and pentane can be corrected by the less affected SF-derived maturity parameter. Reversal to lower apparent SF-derived maturity in thermally and TSR cracked fluids can, on the other hand, be corrected by considering the less affected butane and pentane isomer ratios. Overall, maturities calculated using VLH composition correspond well with fluid type defined based on phase behaviour and source-rock kinetics, thereby putting forward new tools to quantify thermal maturity of reservoir fluids that may be applicable in other petroleum systems.

48‐4: Distinguished Paper: Backside Bonding for Extremely Narrow Bezel at the Bottom of Flexible Displays

We developed a novel method to minimize the bezel of flexible displays through backside bonding of a chip on film, resulting in the bezel width of less than 500 μm as compared to 1000 μm of conventional displays. The metal embedded in polyimide (MEP) layer is placed between the first and second polyimide (PI) substrates and connected to the metal lines of the backplane via the MEP contact (M‐CNT) hole. Subsequently, the nonconductive film (NCF) bonding and intense pulsed light sintering are performed using conductive ink. Conductive ink as the interconnect material capable of low‐temperature sintering is applied to avert thermal degradation and crack. At a high temperature (65 ℃) and humidity (90% relative humidity), the contact resistance was a drivable level for the display after 240 h. The normalized strain in the M‐CNT hole and MEP area were less than 0.4, indicating the absence of cracks during the NCF bonding. These results demonstrated that the backside bonding method was suitable for extremely narrow bezels of the nextgeneration flexible displays.

Machine learning approach with a posteriori-based feature to predict service life of a thermal cracking furnace with coking deposition

A thermal cracking furnace is an important equipment in the petrochemical industry that is typically used for breaking long hydrocarbons into short chains and producing coke as a byproduct. Deposition of the generated coke increases the temperature at the outside coil wall, necessitating regular furnace maintenance to prevent coil failure. Therefore, this study proposed a machine learning approach with a posteriori-based feature to predict the service life of the furnace to runtime failure. The proposed approach consists of a two-level machine learning model, which aims to improve prediction accuracy and reduce feature sensitivity. The label is classified as a week-range label, which can be categorized by classification criteria into three classes: weekly, bi-weekly, and quarter-weekly. The first-level model is utilized to extract sensor features into the posterior probability class label score. These scores are then processed and sorted into moving windows to generate features for the second-level model. The results showed that the proposed model could extract process variation and identify service needs, which improved classification accuracy by 23.94 % and 17.67 % for the clean and coke-contaminated datasets compared to the conventional classification model, respectively. Additionally, the most general class range (quarter-weekly) provided the best performance compared to the bi-weekly and weekly classes. Therefore, the model has the potential for the prediction of the furnace service life under pseudo-steady state conditions, where coking evolves gradually over time.

The impact of bio-oil on the structure, rheology, and adhesion properties of lignin-modified asphalt

This research investigates the efficacy of bio-oil as a sustainable modifier for lignin-modified asphalt (LMA), aiming to enhance its performance characteristics. Utilizing Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), the study analyzes the chemical and microstructural changes induced by bio-oil in LMA. Rheological properties were evaluated using Dynamic Shear Rheometry (DSR), revealing that the addition of 5%–10% bio-oil to LMA significantly reduced stiffness and brittleness, improving ductility and fatigue resistance. For instance, LMAs with 10% bio-oil demonstrated a fatigue life at 2.5% strain comparable to unmodified asphalt. Additionally, bio-oil inclusion increased adhesive strength between asphalt and aggregates, enhancing moisture resistance. Low-temperature properties assessed by dynamic mechanical analysis (DMA) showed improved flexibility and thermal crack resistance with bio-oil addition. These findings underscore the potential of bio-oil in developing high-performance, sustainable asphalt binders, contributing to the advancement of eco-friendly road construction materials.

Experimental investigation on the origin of carbonaceous materials in the fault zone of the Wenchuan earthquake

Carbonaceous materials in seismic fault zones may considerably influence seismic fault slip; however, the formation mechanism of carbonaceous materials remains unclear. In this study, we proposed a novel hypothesis for the formation of carbonaceous materials in fault gouge. Thus, we conducted a CO2 hydrogenation experiment in a high-temperature reactor at a co-seismic temperature, with fault gouge formed during the Wenchuan earthquake as the catalyst. Our experimental results demonstrate that carbonaceous materials in fault zones are formed on the fault gouge during the chemical reaction process, suggesting that the carbonaceous materials are possibly generated from the catalytic hydrogenation of CO2, followed by thermal cracking of its products. The results of this study provide a theoretical basis for understanding fault behavior and earthquake physics.

KARAKTERISTIK PRODUK CAIR CO-PYROLYSIS SAMPAH PLASTIK DAN PELUMAS BEKAS

The increasing usage of plastic is proportional to the amount of plastic waste today. The plastic usage makes the human live easier especially for packaging purposes. However, it also has a negative impact to the environment. This is due to it cannot easily decompose. Therefore, it can reduce the level of soil fertility. Besides plastic, lubricant waste from motor vehicles can induce an environmental problem as well since it is categorized of hazardous material (B3) waste. Currently, the use of plastic waste has been widely carried out by correlating into liquid fuel through thermal cracking or pyrolysis treatment. It produces liquid and it can be used as an alternative liquid fuel. This study uses the co-pyrolysis method for treating the used plastic waste with used lubricants. The composition ratios used are 10:0, 10:2, 10:4, 10:6, and 10:8. The highest acquisition of liquid products was in the composition ratio of 10:6 as much as 24.67% with a calorific value of 11015.33 cal/g. Then the highest calorific, density, and viscosity values were obtained, namely at the 10:8 composition ratio of 11061.67 cal/g, 0.8906 g/mL, and 0.927 cSt. It was concluded that the mixing of used lubricants in the co-pyrolysis of LDPE plastic waste was able to increase the calorific value of the liquid product produced.