Catalyst Development

The biofuel industry is rapidly growing with a promising role in producing renewable energy and tackling climate change. Nanotechnology has tremendous potential to achieve cost-effective and process-efficient biofuel industry. Various nanomaterials have been developed with unique properties for enhanced biofuel production/utilization. The way forward is to develop nanotechnology-based biofuel systems at industrial scale.

This study aims to examine the effect of various advanced catalysts on tire waste pyrolysis oil using a small pilot-scale pyrolysis reactor with a capacity of 20 L. The catalytic pyrolysis with activated alumina (Al2O3) catalyst produced maximum liquid oil (32 wt.%) followed by activated calcium hydroxide (Ca(OH)2) (26 wt.%), natural zeolite (22 wt.%) and zeolite (H-SDUSY) (14 wt.%) catalysts, whereas liquid oil yield of 40% was obtained without catalyst. The gas chromatography-mass spectrometry results confirmed the pyrolysis liquid oil produced without catalyst consist of up to 93.3% of mixed aromatic compounds. The use of catalysts decreased the concentration of aromatic compounds in liquid oil down to 60.9% with activated calcium hydroxide, 71.0% with natural zeolite, 84.6% with activated alumina, except for synthetic zeolite producing 93.7% aromatic compounds. The Fourier-transform infrared spectroscopy data revealed that the mixture of aromatic and aliphatic hydrocarbon compounds were found in all liquid oil samples, which further confirmed the gas chromatography results. The characteristics of pyrolysis liquid oil had viscosity (1.9 cSt), density (0.9 g/cm3), pour point (-2 °C) and flash point (27 °C), similar to conventional diesel. The liquid oil had higher heating values, key feature of a fuel, in the range of 42-43.5 MJ/kg that is same to conventional diesel (42.7 MJ/kg). However, liquid oil requires post-treatments, including refining and blending with conventional diesel to be used as a transport fuel, source of energy and value-added chemicals.

Catalytic steam reforming of model oxygenates of bio-oil for hydrogen production was studied over La modified Ni/CeO 2 –ZrO 2 catalysts. The catalysts were prepared by an impregnation-co-precipitation method and characterized by various characterization techniques. Characterization results revealed that a homogeneous CeO 2 –ZrO 2 –La 2 O 3 (CeZrLa) solid solution was formed during support preparation and the Ni-impregnated catalysts demonstrated strong metal-support interaction. The hydrogen selectivity for the catalyst doped with 5 wt% La 2 O 3 was significantly higher than that for other La content, and CO and CH 4 selectivity also reduced. Conversion showed a sharp rise with increasing temperature from 600 to 800 °C, whereas hydrogen yield and selec-tivity exhibited maxima at 700 °C. At higher temperature, conversion increased due to steam reforming of oxy-genates, while hydrogen yield decreased since the water gas shift reaction proceeds in the reverse direction. Increasing the space–time from 350 to 700 g cat s/g bio-oil , conversion increased from 60 to 85 % and hydrogen yield increased from 42 to 70 % due to the availability of greater contact time of the reactants with the catalyst. No significant decrease in selectivity or conversion was observed for 20 h, indicating that the Ni/CeZrLa (5) catalyst is quite stable. In the spent catalyst obtained after reaction, there is evidence of formation of La 2 O 2 CO 3 , which plays a key role in coke gasification and prolonged activity of the catalyst. Negligible coke deposition was found for the spent Ni/CeZrLa (5) catalyst compared to the undoped catalyst. The results revealed that the presence of lanthana helps in enhancing catalyst life by providing resistance to coking.

Textile industry is one of the major industries worldwide and produces a huge amount of coloured effluents. The presence of coloured compounds (dyes) in water change its aesthetic value and cause serious health and environmental consequences. However, the present investigation was carried out to minimize and reduce the colour compounds discharged by the textile industries through a nano-scaled catalyst. This study is mainly focused on the explanation of nanoparticles aggregation by deposition on natural zeolite, and utilization of this natural zeolite as supported material to nano zerovalent iron (NZ-nZVI) in the form of liquid slurry with sodium percarbonate acting as an oxidant in a Fenton like system for the removal of synthetic CI acid orange 52 (AO52) azo dye, in textile effluent. The nano-scaled zerovalent irons were synthesized by borohydride method in ethanolic medium. UV–vis spectrophotometry, FTIR, EDX, SEM, and XRD (powdered) analysis were used for the investigations of surface morphology, composition, and properties of natural zeolite supported nZVI and study the dye removal mechanism. The XRD spectrum revealed that clinoptilolite is the major component of natural zeolite used, while EDX found that the iron content of NZ-nZVI was about 9.5 %. The introduction of natural zeolite as supporting material in the formation of iron nanoparticle resulted in the partial reduction of aggregation of zerovalent iron nanoparticles. The findings revealed that the 94.86 % removal of CI acid orange 52 dye was obtained after 180 min treatment at 15 mg/L initial dye concentration. The highest rapid dye removal of about 60 % was achieved within the first 10 min of treatment at the same dye concentration. Furthermore, the actual dyeing effluent including green, magenta, and the blended colour was successfully decolourized by natural zeolite-supported nZVI/SPC Fenton process. It is concluded that the acceleration of corrosion of NZ-nZVI, breaking of azo bond, and consumption of Fe2+ were the possible mechanisms behind the removal of AO52 dye. It is also recommended that NZ-nZVI/SPC Fenton process could be a viable option for effluent and groundwater remediation.

Direct methanol fuel cells (DMFCs) generate electricity in a clean and efficient way, so they are a valuable alternative to traditional environmentally harmful technologies. Portable power sources are one of the applications of passive DMFCs. One of the requirements in these devices is the use of high alcohol concentration. Methanol permeation across the polymer electrolyte membrane (methanol crossover) causes a loss of fuel cell efficiency as the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) occur simultaneously at the cathode. To develop methanol-tolerant catalysts with suitable activity, different PtM/C and PtMRu/C combinations with M = Co or Fe were prepared by a modified impregnation method. The synthesized catalysts were studied to determine the role of the components in enhancing the ORR and simultaneously discouraging the MOR. The materials were characterized by TEM, XPS and EDS. Well-distributed particles for all the catalysts were shown by TEM. XPS spectra revealed that the method produces a great amount of metallic Pt. The electrochemical characterization was carried out by linear sweep voltammetry and cyclic voltammetry, in a three-electrode electrochemical cell with a glassy carbon rotating disk electrode covered with a thin catalytic layer and a Nafion® film as the working electrode. Binary and ternary catalysts have a good activity for the ORR. However, the enhanced activity of binary catalysts is lost when the ORR is studied in the presence of methanol. Ternary catalysts containing Ru showed higher methanol-tolerance, regardless of the composition.

Microwave pyrolysis was performed on waste engine oil pre-mixed with different amounts of metallic-char catalyst produced previously from a similar microwave pyrolysis process. The metallic-char catalyst was first prepared by pretreatment with calcination followed by analyses to determine its various properties. The heating characteristics of the mixture of waste oil and metallic-char during the pyrolysis were investigated, and the catalytic influence of the metallic-char on the yield and characteristics of the pyrolysis products are discussed with emphasis on the composition of oil and gaseous products. The metallic-char, detected to have a porous structure and high surface area (124 m2/g), showed high thermal stability in a N2 atmosphere and it was also found to have phases of metals and metal oxides attached or adsorbed onto the char, representing a potentially suitable catalyst to be used in pyrolysis cracking process. The metallic-char initially acted as an adsorptive-support to adsorb metals, metal oxides and waste oil. Then, the char became a microwave absorbent that absorbed microwave energy and heated up to a high temperature in a short time and it was found to generate arcing and sparks during microwave pyrolysis of the waste oil, resulting in the formation of hot spots (high temperature sites with temperature up to 650 °C) within the reactor under the influence of microwave heating. The presence of this high temperature metallic-char, the amounts of which are likely to increase when increasing amounts of metallic-char were added to the waste oil (5, 10, and 20 wt% of the amount of waste oil added to the reactor), had provided a reducing chemical environment in which the metallic-char acted as an intermediate reductant to reduce the adsorbed metals or metal oxides into metallic states, which then functioned as a catalyst to provide more reaction sites that enhanced the cracking and heterogeneous reactions that occurred during the pyrolysis to convert the waste oil to produce higher yields of light hydrocarbons, H2 and CO gases in the pyrolysis products, recording a yield of up to 74 wt% of light C5-C10 hydrocarbons and 42 vol% of H2 and CO gases. The catalytic microwave pyrolysis produced 65-85 wt% yield of pyrolysis-oil containing C5-C20 hydrocarbons that can potentially be upgraded to produce transport-grade fuels. In addition, the recovered pyrolysis-gases (up to 33 wt%) were dominated by aliphatic hydrocarbons (up to 78 vol% of C1-C6 hydrocarbons) and significant amounts of valuable syngas (up to 42 vol% of H2 and CO in total) with low heating values (LHV) ranging from 4.7 to 5.5 MJ/m3, indicating that the pyrolysis-gases could also be used as a gaseous fuel or upgraded to produce more hydrogen as a second-generation fuel. The results indicate that the metallic-char shows advantages for use as a catalyst in microwave pyrolysis treatment of problematic waste oils.

A carbonization-sulfonation method was utilized in synthesizing sulfonated mesoporous catalysts from palm tree biomass. Brunauer-Emmet-Teller (BET), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), and field emission scanning emission microscopy (FE-SEM) analyses were used to evaluate the structural and textural properties of the catalysts. Further, Fourier transform infrared (FT-IR) spectroscopy and titrimetric analyses measured the strong acid value and acidity distribution of the materials. These analyses indicated that the catalysts had large mesopore volume, large surface area, uniform pore size, and high acid density. The catalytic activity exhibited by esterifying used frying oil (UFO) containing high (48%) free fatty acid (FFA) content further indicated these properties. All catalysts exhibited high activity, with sPTS/400 converting more than 98% FFA into fatty acid methyl esters (FAMEs). The catalyst exhibited the highest acid density, 1.2974 mmol/g, determined by NaOH titration. This is outstanding considering the lower reaction parameters of 5 h, 5:1 methanol-to-oil ratio, and a moderate temperature range between 100 and 200 °C. The study further illustrates the prospect of converting wastes into highly efficient, benign, and recyclable solid acid catalysts.

Energy Frontier Research Centers have been developed by the Department of Energy to accelerate research synergism among experimental and theoretical scientists in catalysis. The overall goal is to advance tools of synthesis, characterization, and computation of solid catalysts to design and predict catalytic properties at the atomic level. The Center for Atomic-Level Catalyst Design (CALC-D) has the goal of significantly advancing: (a) the tools of materials synthesis, allowing catalysts identified by computation to be prepared with atomic-level precision, (b) characterization methods such as advanced spectroscopy to understand surface structures of the working catalyst unambiguously, and (c) the ability of computational catalysis to accurately model reactions at working conditions.