Catalytic pyrolysis of biomass over zeolites for bio-oil and chemical production: A review on their structure, porosity and acidity co-relation

The oxygenated compounds found in bio-oil limit their application as a transportation fuel. Several studies were reported on eliminating the oxygenated components from bio-oil so as to improve its fuel properties. This work is dedicated to studying the shape selectivity, porosity, structure, acidity of zeolites and their effect in bio-oil and chemicals production. The unified pore size, specific structure, controlled Si/Al ratio, unique channels and circular entrances, mesoporosity, and acidity are the utmost discerning parameters for aromatics production and deoxygenation reaction. The conversion of biomass-derived oxygenates to aromatics using zeolite is subjected to the reactants entering the pore, conversion inside the pore, and diffusing out of the products from the zeolite pores. These approaches were considered for an in-depth understanding of zeolite properties, which will enhance the fundamental understanding of pyrolysis.

Al-Hussain S, E. A. Zaki M, H. Asghar B, A. Muhammad Z. Synthesis of spiropyrazoles under organic and nonorganic catalysis

Abstract:

Spiropyrazoles display many biological biological activities such as antitumor, vasodilation, analgesic, phosphodiesterase inhibitors, aldosterone antagonistic, anabolic, androgenic, anti-inflammatory, progestational and salt-retaining activities and they also exert neuroprotection in dopaminergic cell death. Many efforts have been made to obtain these derivatives with high yield and excellent regio-, diastereo- and enantioselectivities. Most of the spiroprazole synthesis methods were proceeded in good to excellent yield in the presence of organic catalysts as for examples squaramide, NHC pre-catalyst, pyrrole derivatives, bis-oxazoline, DMAP, DABCO, thiourea derivatives, DBU, acetic acid and quinoline catalysts. In addition, the inorganic and organo-metallic catalysts have been proven their efficiency in synthesis of various types of spiro-pyrazoles in excellent yield. Thus, in this review we have compiled all citations for the synthesis of spiropyrazoles in the presence of various types of catalysts such as organic, inorganic, and metalorganic catalysts in the range 2020 to 2012. This review article is a useful compilation for researchers interested in the synthesis of spiropyrazole derivatives and will assist them in selecting appropriate catalysts for preparation of their spiropyrazoles.

Recycling Rusty Iron with Natural Zeolite Heulandite to Create a Unique Nanocatalyst for Green Hydrogen Production

Corrosion-induced iron rust causes severe danger, pollution, and economic problems. In this work, nanopowders of Fe2O3 and Fe2O3/zeolite are synthesized for the first time using rusted iron waste and natural zeolite heulandite by chemical precipitation. The chemical composition, nanomorphologies, structural parameters, and optical behaviors are investigated using different techniques. The Fe2O3/zeolite nanocomposite showed smaller sizes and greater light absorption capability in visible light than Fe2O3 nanopowder. The XRD pattern shows crystalline hematite (α-Fe2O3) with a rhombohedral structure. The crystallite sizes for the plane (104) of the Fe2O3 and Fe2O3/zeolite are 64.84 and 56.53 nm, respectively. The Fe2O3 and Fe2O3/zeolite have indirect bandgap values of 1.87 and 1.91 eV and direct bandgap values of 2.04 and 2.07 eV, respectively. Fe2O3 and Fe2O3/zeolite nanophotocatalysts are used for solar photoelectrochemical (PEC) hydrogen production. The Fe2O3/zeolite exhibits a PEC catalytic hydrogen production rate of 154.45 mmol/g.h @ 1 V in 0.9 M KOH solution, which is the highest value yet for Fe2O3-based photocatalysts. The photocurrent density of Fe2O3/zeolite is almost two times that of Fe2O3 catalyst, and the IPCE (incident photon-to-current conversion efficiency) reached ~27.34%@307 nm and 1 V. The electrochemical surface area (ECSA) values for Fe2O3 and Fe2O3/zeolite photocatalysts were 7.414 and 21.236 m2/g, respectively. The rate of hydrogen production for Fe2O3/zeolite was 154.44 mmol h-1/g. This nanophotocatalyst has a very low PEC corrosion rate of 7.6 pm/year; it can retain ~97% of its initial performance. Therefore, the present research can be applied industrially as a cost-effective technique to address two issues at once by producing solar hydrogen fuel and recycling the rusted iron wires.

Formic acid as a hydrogen storage material – development of homogeneous catalysts for selective hydrogen release

Liquid energy: formic acid is an ideal candidate for catalytic release and storage of hydrogen.