No abstract

The cyclisation of citronellal to isopulegol is a significant intermediate stage in the production of menthols. In this research work, the effects of acid treatment on montmorillonite clay have been investigated and used in citronellal cyclisation reactions. Furthermore, the effects of acid treatment and hetero-poly acid impregnation have been determined on the textural and catalytic properties of montmorillonite clay. The designed catalysts were characterized by XRD, N2 sorption, and NH3- TPD techniques. Acid treatment of montmorillonite resulted in the enhancement of surface area and pore volume. The catalytic activity and selectivity parameters were lessened due to the severe leaching of Al ions from tetrahedral crystalline structures (e.g., weakened structure and loss of acidity). Among all prepared materials, the heteropoly acid supported HCl treated montmorillonite catalyst was observed as a more active, stable, and selective catalyst that showed the highest catalytic performance in citronellal cyclisation under optimized process parameters. The catalytic activity and selectivity were enhanced with rising mesoporosity and acidity parameters due to HCl acid treatment and HPA impregnation.

Hydrothermal liquefaction (HTL) is a thermochemical depolymerization technology, also known as hydrous pyrolysis, that transforms wet biomass into biocrude and valuable chemicals at a moderate temperature (usually 200–400 °C) and high pressure (typically 10–25 MPa). In HTL, water acts as a key reactant in HTL activities. Several properties of water are substantially altered as the reaction state gets closer to the critical point of water, which can result in quick, uniform, and effective reactions. The current review covers the HTL of various feedstocks, especially lignocellulosic and high protein-containing feeds with their in-depth information of the chemical reaction mechanisms involved in the HTL. Further, this review gives insight and knowledge about the influencing factors such as biomass pretreatment, process mode, process conditions, etc., which could affect the efficiency of the hydrothermal process and biocrude productivity. In addition, the latest trends, and emerging challenges to HTL are discussed with suitable recommendations.

No abstract

No abstract

No abstract

Pakistan is the world largest lignite bearing country in the world due to the Thar coal reserves. Sulfur contained in this coal need to be removed prior to combustion. Oxidative alkali leaching in dissolved oxygen technique was used to remove the sulfur from Thar coal. This method removed enough all three types of sulfur; about 90% pyretic sulfur, 78% organic sulfur and 50% sulfate sulfur and more than 82S% of total sulfur removal was achieved. Effect of various reaction parameters were observed, it was investigated that reaction time and partial pressure of oxygen has positive effect on the desulfurization, higher the reaction time and oxygen partial pressure higher the degree of desulfurization, also the desulfurization increased with increase in reaction temperature and alkali concentration till some optimum value and then decreases with further increase in value of temperature and concentration of alkali, although desulfurization was observed maximum with minimum particle size. Coal was also characterized with Thermogravimetric Analysis (TGA) and Testo smoke number to investigate the combustion behavior of processed coal. It was observed that combustion properties of processed coal were improved and black smoke in processed coal was reduced.

Pakistan is the world largest lignite bearing country in the world due to the Thar coal reserves. Sulfur contained in this coal need to be removed prior to combustion. Oxidative alkali leaching in dissolved oxygen technique was used to remove the sulfur from Thar coal. This method removed enough all three types of sulfur; about 90% pyretic sulfur, 78% organic sulfur and 50% sulfate sulfur and more than 82S% of total sulfur removal was achieved. Effect of various reaction parameters were observed, it was investigated that reaction time and partial pressure of oxygen has positive effect on the desulfurization, higher the reaction time and oxygen partial pressure higher the degree of desulfurization, also the desulfurization increased with increase in reaction temperature and alkali concentration till some optimum value and then decreases with further increase in value of temperature and concentration of alkali, although desulfurization was observed maximum with minimum particle size. Coal was also characterized with Thermogravimetric Analysis (TGA) and Testo smoke number to investigate the combustion behavior of processed coal. It was observed that combustion properties of processed coal were improved and black smoke in processed coal was reduced.