The porous structure of cylindrical and ring-shaped char material was developed by partial steam gasification. Micropore and mesopore structures of active carbons with various forms of burn-off were evaluated by nitrogen adsorption/desorption isotherms. Parameters of the Dubinin- Radushkevich equation were calculated as well as the micropore size distribution by the Horvath- Kawazoe method. The results of textural investigations showed that more uniform micropore structure and better mechanical properties were found for ring-shaped active carbons.
This paper shows the possibility that the mineral coal existing in the mining basins of northern Spain have a high added value. This would facilitate its future use in different fields such as new materials, nanotechnology, energy use in situ, coal bed methane, enhanced coal bed methane and coalmine methane.
An analytical study of mineral coal samples is carried out. The samples come from two deposits located in coal basins of the Cantabrian Mountains. The duly prepared samples are subjected to an activation process. Within this transformation, different treatments are applied to different sub-samples. Some of the sub-samples suffer a previous demineralization by successive attacks with acids, followed by oxidation and pyrolysis. Finally, all of them are activated with CO2 and H2O(steam).
The carbonaceous products resulting from each treatment are characterised. The results show that all the pre-treatments used were positive for the textural development of the materials. Likewise, proper management of the processes and of the different operating variables allows the procurement of carbonaceous materials with a “tailor-made” structural development of the coal type. This material receives the name “activated” and can be employed in specific processes.
It is estimated that the amount of used car tires in the European Union in 2016 was established at the level of 3,515,000 Mg, which is undoubtedly a problem from the point of view of engineering and environmental protection. An alternative to storing this waste in landfills is their pyrolysis. As a result of thermal decomposition, calorific value products (oil and gas fraction) are obtained, as well as a solid residue, which due to its composition and properties can be processed into a high quality carbon sorbent. For this purpose, various methods of modification of the pyrolyzate are used, both involving physical and chemical activation. This article presents the characteristics of solid residue after the pyrolysis of rubber tires running at a temperature of about 400°C, which included an analysis of chemical composition (XRF and IR), mineralogical composition (XRD, SEM-EDS) and textural characteristics. Additionally, for the purpose of activation, the sample was treated with nitrogen at a temperature of 550°C. The mineralogical analysis showed that the dominant mineral component is carbon. In addition, the presence of quartz, calcite and sphalerite was observed. Analysis of the chemical composition suggests that due to the high carbon content (about 80% by mass) it is possible for a carbon sorbent from the analyzed waste to be obtained. However, previous preliminary studies did not allow a material constituting a substitute for activated carbon to be obtained, because the applied modification only slightly increased the BET specific surface area, which reached the value of approx. 85 m2/g. Based on the analysis of the pore size distribution of the 2 tested samples, it was found to be homogeneous/modal with a micro/mesoporous nature, while the shape of the hysteresis loop suggests the presence of “bottle shape” pores. Due to the relatively high content of zinc, the composition of waste (about 4% of mass), the possibility of recovery of this element should also be considered.
There is general agreement that primary pyrolysis products of end-of-life tyres should be valorised to improve the economics of pyrolysis. In this work, tyre pyrolysis char (TPC) is produced in a pyrolysis pilot plant designed and built at our home university. The produced TPC was upgraded to tyre-derived activated carbon (TDAC) by activation with CO2, and then characterised using stereological analysis (SA) and nitrogen adsorption at 77 K. SA showed that the grains of TPC and TDAC were quasi- spherical and slightly elongated with a 25% increase in the mean particle cross-section surface area for TDAC. The textural properties of TDAC demonstrated the BET and micropore surface areas of 259 and 70 m2/g, respectively. Micropore volume and micropore surface area were 5.8 and 6.7 times higher for TDAC than TPC at 2 nm, respectively. The n-hexane adsorption was investigated using experiments and modelling. Eight adsorption isotherms along with three error functions were tested to model the adsorption equilibrium. The optimum sets of isotherm parameters were chosen by comparing sum of the normalized errors. The analysis indicated that the Freundlich isotherm gave the best agreement with the equilibrium experiments. In relation to different activated carbons, the adsorption capacity of TDAC for n-hexane is about 16.2 times higher than that of the worst reference material and 4.3 times lower than that of the best reference material. In addition, stereological analysis showed that activation with CO2 did not change the grain’s shape factors. However, a 25% increase in the mean particle cross-section surface area for TDAC was observed.
Catalytic properties of activated carbons oxidized, treated with N-compounds, and promoted with copper were studied in selective catalytic reduction NOX by ammonia (NH3-SCR). The modification of the catalysts consisted of a series of steps (pre-oxidation of activated carbon, impregnation with urea, impregnation with copper). The physicochemical properties of the obtained samples were determined using X-ray diffraction, FT-IR spectroscopy, and low-temperature N2 sorption. The modification with copper improved the catalytic activity and stability of the catalysts. All the functionalized carbon doped with copper reached more than 90% of NO conversion and CO2 did not exceed 240 ppm at 220 ◦C. The sample doped with 5 wt.% Cu had the maximum NO conversion of 98% at 300 ◦C. The maximum N2O concentration detected for the same sample was only 55 ppm, which confirmed its selectivity.
The cyclic Electrothermal Temperature Swing Adsorption (ETSA) process in a fixed-bed column with Supersorbon K40 activated carbon (AC) was applied to remove propan-2-ol (IPA) from air. The bed was electrothermally regenerated using direct resistive heating method. The tests were performed in the range of operating parameters: IPA loading 0.18-0.26 kg/kg, voltage 19.5 V, set-point temperature 393–403 K, nitrogen flow rate 0.12 m3/h.
The analysis revealed, that raising the bed temperature resulted in an increase of desorption degree of adsorbate, reduction of regeneration time and an increase in the energy consumption. The application of insulation enabled reduction of energy consumption and regeneration time by 27% and 10%, respectively.