Cost-effective activated carbons for CO₂ adsorption were developed from molasses using H₂SO₄, H₃PO₄, HCl, NaOH, and KOH as activating agents. At the temperature of 0 °C and a pressure of 1 bar, CO₂ adsorption equal to 5.18 mmol/g was achieved over activated carbon obtained by KOH activation. The excellent CO₂ adsorption of M-KOH can be attributed to its high microporosity. However, activated carbon prepared using HCl showed quite high CO₂ adsorption while having very low microporosity. The absence of acid species on the surface promotes CO₂ adsorption over M-HCl. The pore size ranges that are important for CO₂ adsorption at different temperatures were estimated. The higher the adsorption temperature, the more crucial smaller pores were. For 1 bar pressure and temperatures of 0, 10, 20, and 30 °C, the most important were pores equal and below: 0.733, 0.733, 0.679, and 0.536 nm, respectively.

Titanium-containing mesoporous silica catalysts with different Ti contents were prepared by the sol–gel method, whereby the molar ratios of silicon to titanium in the crystallization gel amounted to, respectively, 40:1, 30:1, 20:1 and 10:1. The produced Ti-MCM-41 materials were characterized by the following instrumental methods: XRD, UV-Vis, FT-IR, SEM, and XRF. Textural parameters were also determined for these materials by means of the N₂ adsorption/desorption method. The activities of these catalysts were investigated in the α-pinene isomerization process. The most active catalyst was found to be the material with the molar ratio of Si:Ti equal to 10:1, which contained 12.09 wt% Ti. This catalyst was used in the extended studies on the α-pinene isomerization process, and the most favorable conditions for this reaction were found to be temperature of 160 °C, reaction time of 7 h, with the catalyst composition of 7.5 wt% relative to α-pinene. These studies showed that the most active catalyst, at the best reaction conditions, allowed for the attainment of 100% conversion of α-pinene over a period of 7 h. After this time the selectivities (in mol%) of the main products were as follows: camphene (35.45) and limonene (21.32). Moreover, other products with lower selectivities were formed: γ-terpinene (4.38), α-terpinene (8.12), terpinolene (11.16), p-cymene (6.61), and α-phellandrene (1.58).

In the current study, the isomerization of geraniol over a natural sepiolite as a catalyst was investigated and optimized. Prior to application in the isomerization process, the physical and chemical properties of sepiolite were characterized using a battery of instrumental techniques, including XRD, nitrogen adsorption at 77 K, SEM, EDXRF, UV–Vis and FT-IR. Results indicated that geraniol isomerization is very complicated due to the large number of reactions taking place. The catalytic studies showed that the main reaction products were β-pinene, ocimenes, linalool, nerol, citrals, thunbergol and isocembrol; all chemical products with commercial applications. The quantity of each of these products depended on the temperature, catalyst content and reaction time employed in the isomerization process. During the current study, these parameters were varied in a step-wise approach over the ranges 80–150 °C (temperature), 5–15 wt% catalyst content and reaction time of 15–1440 min. As linalool is one of the most commercially important reaction products, the geraniol isomerization method was studied to identify conditions producing the highest selectivity for this compound. The most beneficial conditions for geraniol conversion and linalool formation were established as a temperature of 120 °C, catalyst content of 10 wt% and a reaction time of 3 h. Graphic

This work presents studies on the preparation of porous carbon materials from waste biomass in the form of orange peels, coffee grounds, and sunflower seed husks. The preparation of activated carbons from these three waste materials involved activation with KOH followed by carbonization at 800 °C in an N₂ atmosphere. This way of obtaining the activated carbons is very simple and requires the application of only two reactants. Thus, this method is cheap, and it does not generate much chemical waste. The obtained activated carbons were characterized by XRD, SEM, XPS, and XRF methods. Moreover, the textural properties, acidity, and catalytic activity of these materials were descried. During catalytic tests carried out in the alpha-pinene isomerization process (the use of the activated carbons thus obtained in the process of alpha-pinene isomerization has not been described so far), the most active were activated carbons obtained from coffee grounds and orange peels. Generally, the catalytic activity of the obtained materials depended on the pore size, and the most active activated carbons had more pores with sizes of 0.7–1.0 and 1.1–1.4 nm. Moreover, the presence of potassium and chlorine ions in the pores may also be of key importance for the alpha-pinene isomerization process. On the other hand, the acidity of the surface of the tested active carbons did not affect their catalytic activity. The most favorable conditions for carrying out the alpha-pinene isomerization process were the same for the three tested activated carbons: temperature 160 °C, amount of the catalyst 5 wt.%, and reaction time 3 h. Kinetic studies were also carried out for the three tested catalysts. These studies showed that the isomerization over activated carbons from orange peels, coffee grounds, and sunflower seed husks is a first-order reaction.