Calcined and acid-leached kaolin impregnated with Fe(NO₃)₃·9H₂O (6.6 wt. % Fe₂O₃) was developed as an inexpensive bifunctional catalyst for the slow fixed-bed pyrolysis of polypropylene (PP) and low-density polyethylene (LDPE). Experiments were run with catalyst-to-plastic mass ratios of 1:4, 1:2, and 1:1 in a quartz tube reactor heated from 25 to 800 °C. For PP, increasing the Fe/kaolin loading progressively raised non-condensable gas from 26 wt. % to 44 wt. % and drove liquid aromatics from 27.9% to 72.3%, while combined paraffins olefins fell to 2.5% and wax exhibited a 46 → 24 → 36 wt. % trend. In contrast, LDPE at a 1:4 ratio already yielded 56 wt. % oil and only 22 wt. % wax; further catalyst addition mainly enhanced CH₄/CO-rich pyrolysis gas (PyGas) and char without substantially boosting aromatics. Gas analysis confirmed that Fe₂O₃ reduction and kaolin de-hydroxylation generated in situ H₂O, CO, and H₂. Given the catalyst’s low cost, regenerability, and ability to valorize the two most abundant waste polyolefins within the same reactor, the process offers a scalable route to flexible fuel and gas production from mixed plastic streams.

The possibility of processing sunflower husk into a carbon-containing material carbonizate was investigated. This material is considered promising for use as a functional technological additive in the production of rubber technical products. The carbonizate was obtained by thermal conversion of sunflower husk in an inert atmosphere, followed by evaluation of its composition and physicochemical characteristics. TGA showed that the main thermal decomposition processes of biomass components occur in the temperature range of 200–550 °C, which determines the choice of the carbonization temperature regime. GC analysis of the pyrolysis products revealed the formation of gas, liquid, and solid fractions. The gaseous products contained energy-rich components, including H2, CO, CH4, and light hydrocarbons; their higher heating value was 14.27 MJ/Nm3. The liquid fraction consisted mainly of oxygen-containing and aromatic compounds, with a heating value of 13.71 MJ/kg. The obtained carbonizate was characterized by a carbon content of 48.12 wt.%, low ash content of 3.5 wt.%, an alkaline surface character (pH = 9), a specific surface area of 27.3 m²/g, and a moderate degree of micropore development. The average particle size after grinding was 18.89 μm, which meets the requirements for dispersed fillers. In addition, a pilot-scale biomass carbonization technology with a processing capacity of at least 150 kg/h was developed, confirming the feasibility of scaling up the process.

Plastic waste and sewage sludge (SS) are abundant, heterogeneous waste streams whose utilization and recycling are constrained by contamination, variable composition, and limited resource recovery. This review evaluates their integrated thermochemical conversion, focusing on co-incineration, co-pyrolysis, co-gasification, hydrothermal co-carbonization, hydrothermal co-liquefaction, and the use of SS-derived char (SSC) and sewage sludge ash (SSA) as catalytic materials. Co-processing benefits arise from complementary feedstock properties: plastics provide high carbon, hydrogen, volatile matter (VM), and heating value, whereas SS contributes oxygenated intermediates and mineral phases containing Si, Al, Fe, Ca, Mg, and P. Among the reviewed routes, co-pyrolysis shows the strongest evidence of non-additive interactions, including hydrogen transfer, altered decomposition kinetics, and changes in liquid composition. Co-gasification can enhance H₂ formation and tar conversion, while hydrothermal routes are especially attractive for wet SS but remain comparatively underexplored. The review further distinguishes SSA, dominated by mineral acid–base and redox functionality, from SSC, which combines these mineral effects with adsorption and surface reactions on a porous carbon matrix. Key barriers include catalyst deactivation, chlorine and sulfur poisoning, heavy-metal migration, feedstock variability, and limited pilot-scale validation. Future development requires mechanistic controls, catalyst stability testing, techno-economic analysis, life-cycle assessment, and integrated nutrient recovery to establish practical circular waste-management systems.

Sewage sludge (SS)-derived materials were investigated as low-cost heterogeneous catalytic materials for polystyrene (PS) pyrolysis, focusing on the effects of thermal treatment, HCl leaching, and Fe impregnation. Sewage sludge ash (SSA), sewage sludge char (SSC), and HCl-leached Fe-impregnated sewage sludge char (Fe-LSSC) were evaluated as in-situ catalytic materials. Catalyst-to-PS ratios of 1:1–1:10 were investigated in a horizontal semi-batch tubular reactor operated in an in-situ catalyst–polymer contact mode at 800 °C. Thermal pyrolysis produced 63.9 wt.% PyOil and 12.6 wt.% PyGas. SSA increased the PyOil yield to 78.0 wt.% at 1:10 and promoted lighter aromatics; at 1:1, light aromatics increased to 66.8 wt.%, BTEX from 5.8 to 24.58 wt.%, and PAHs decreased to 11.8 wt.%. SSC showed a weaker, non-monotonic effect, with PyOil decreasing to 54.4 wt.% and PyChar increasing to 4.7 wt.% at 1:2. Fe-LSSC produced the strongest changes, increasing PyGas to 28.0 wt.% at 1:1 and H₂ to 75.3 vol.% at 1:2. The gasoline-range fraction reached 82.1 wt.% at 1:2, while PAHs decreased to 8.79 wt.% at 1:1. Catalyst reuse altered gas composition, whereas thermal regeneration partially restored catalytic behavior. Overall, SS-derived materials exhibited distinct, loading-dependent catalytic functions, while HCl leaching and Fe impregnation enhanced the conversion of PS pyrolysis vapors toward lighter aromatic and gaseous products.

This study examines the specific features of the production technology of granular activated carbon obtained from substandard fine-grained carbon fractions, which are by-products of the special coke industrial production at JSC «Shubarkol Komir.» A technological scheme was developed for producing activated carbon based on this industrial waste, including the methods and conditions for granulation, carbonization, and activation. The physicochemical properties and structural characteristics of the resulting target carbon materials were evaluated. Granular and powdered activated carbons were produced from coke fines with the following composition: 60% coke fines, 35% binder, and 5% chemical activating agent. The temperature dependencies of the activation process were determined. Using adsorption-structural analysis methods, the structure of the activated carbon was studied, revealing a well-developed porous structure that includes mesopores with slit sizes ranging from 2 to 32 nm.