Applied Petrochemical Research (v.4, #1)

Preface for the special issue of the 3rd KACST-Oxford Petrochemical Forum by Peter P. Edwards; Hamid Almegren; Tiancun Xiao; Vladimir Kuznetsov (1-2).
The 3rd KACST-Oxford Petrochemical Research Forum (KOPRC Forum) was held in August 2013, some of the presentations in the forum have been submitted to the special issue of Applied Petrochemical Research. This paper collection covers most of topics of petrochemical technologies including catalyst and catalytic process, polymers, feedstocks and process improvements.
Keywords: Preface; KOPRC Forum; Oxford; KACST

In this article, an overview of the application of selected metal nitrides as ammonia synthesis catalysts is presented. The potential development of some systems into nitrogen transfer reagents is also described.
Keywords: Nitrogen; Hydrogen; Catalysis; Ammonia; Nitrides

Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century’s grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands.
Keywords: Heterogeneous catalysis; Biofuels; Biodiesel; Selective oxidation; Alcohols

In this paper, the use of temperature-programmed oxidation (TPO) is highlighted as a means of interrogating the surface of catalysts. Most studies only concern themselves with the active portion of the catalyst bed; in this study, we examine both the active part and the part that experiences equilibrated gas after reaction. The extent and nature of carbonaceous deposits on both sections of catalyst have been characterised by TPO and reveal that there is significant deposition of low H:C ratio carbonaceous species on catalyst that has only seen equilibrated reaction gas. This has potential implications for the life of the catalyst bed and the activity and selectivity observed.
Keywords: PyGas; Hydrogenation; Temperature programmed oxidation; Carbon deposition

CO2 recycling using microalgae for the production of fuels by M. H. Wilson; J. Groppo; A. Placido; S. Graham; S. A. Morton III; E. Santillan-Jimenez; A. Shea; M. Crocker; C. Crofcheck; R. Andrews (41-53).
CO2 capture and recycle using microalgae was demonstrated at a coal-fired power plant (Duke Energy’s East Bend Station, Kentucky). Using an in-house designed closed loop, vertical tube photobioreactor, Scenedesmus acutus was cultured using flue gas as the CO2 source. Algae productivity of 39 g/(m2 day) in June–July was achieved at significant scale (18,000 L), while average daily productivity slightly in excess of 10 g/(m2 day) was demonstrated in the month of December. A protocol for low-cost algae harvesting and dewatering was developed, and the conversion of algal lipids—extracted from the harvested biomass—to diesel-range hydrocarbons via catalytic deoxygenation was demonstrated. Assuming an amortization period of 10 years, calculations suggest that the current cost of capturing and recycling CO2 using this approach will fall close to $1,600/ton CO2, the main expense corresponding to the capital cost of the photobioreactor system and the associated installation cost. From this it follows that future cost reduction measures should focus on the design of a culturing system which is less expensive to build and install. In even the most optimistic scenario, the cost of algae-based CO2 capture is unlikely to fall below $225/ton, corresponding to a production cost of ~$400/ton biomass. Hence, the value of the algal biomass produced will be critical in determining the overall economics of CO2 capture and recycle.
Keywords: Microalgae; Carbon dioxide; Flue gas; Capture; Techno-economic analysis; Biofuels

Ethanol photoreactions over Au–Pd/TiO2 by A. K. Wahab; S. Bashir; Y. Al-Salik; H. Idriss (55-62).
A prototype Au–Pd/TiO2 catalyst was prepared, characterized and tested for the photoreaction of ethanol. XPS Au4f and Pd3d indicated that the as-prepared material is composed of metallic Au, metallic Pd as well oxidized Pd (Pd2+). Ar ion sputtering (5 min) of the catalyst surface resulted in almost total reduction of Pd2+ to metallic Pd in addition to considerable reduction of surface Ti cations to Ti3+ and Ti2+ cations; XPS Au4f lines were not affected. Transmission electron microscopic studies indicated that Au particles have a mean particle size of about 3.5 nm while Pd particles are smaller 1–1.5 nm in size. UV excitation of the catalyst in ultrahigh vacuum (UHV) conditions resulted in the formation of acetaldehyde and hydrogen in addition to photodesorption of the reactant ethanol. Hydrogen production, representing ca. 30 % of the desorbing products, was delayed compared to acetaldehyde desorption. This was interpreted as due to kinetic effect whereby initially most electrons transferred to the conduction band are trapped by surface hydroxyls as well inevitable presence of oxygen in the powder accelerating acetaldehyde formation (dehydrogenation). Only once most oxygen-containing species have reacted and molecular hydrogen was formed. To our knowledge, this is the first UHV in situ study of hydrogen production from ethanol photocatalytically over M/TiO2 system.
Keywords: Hydrogen production; Ethanol photoreaction; Gold plasmon; Synergism; Ethanol dehydrogenation

The reduction of greenhouse gas emissions is an ever-increasing challenge for production units and power plants in view of the global warming concerns. Carbon dioxide capturing from petrochemical process streams and flares has been recognized as one of the several strategies necessary for mitigating the emission of greenhouse gases into the atmosphere. To keep greenhouse gases at manageable levels, large decrease in CO2 emissions through separation and utilization will be required. Furthermore, carbon dioxide emission potential will become an important factor in technology selection when cost of carbon dioxide emissions is set to be included in the processing cost. This article reviews the potential CO2 separation technologies and its recycling via chemical fixation as bulk chemical products in petrochemical industry. Various separation techniques, such as absorption, adsorption, membrane separation and cryogenic, and utilization processes, such as conversion to carbon monoxide, oxidative dehydrogenation, hydrogenation and polymerization are thoroughly discussed. The technological challenges and recent developments and achievements are also presented.
Keywords: Carbon dioxide; Greenhouse gas (GHG); Carbon capture and utilization (CCU); Catalytic conversion; C1 chemistry; Petrochemical industry

Characterization of polyethylene synthesized by zirconium single site catalysts by Abdulhamid A. Alsaygh; Jehan Al-hamidi; Fares D. Alsewailem; Ibrahim M. Al-Najjar; Vladimir L. Kuznetsov (79-84).
New non-metallocene, bridged-zirconium center catalysts were prepared by Schiff base condensations reaction of two equivalents of appropriate 2-hydroxybenzaldehyde with one equivalent of 4,4′-methylene bis(2-methylcyclohexylamine), and subsequent metathesis reaction with ZrCl4(THF)2, and tested for ethylene polymerization reaction at different conditions. Catalyst productivities were found to be high, in the range of 29.5 × 103 kg/mole·Zr·h to 2.3 × 103 kg/mole·Zr·h, dependents on the polymerization condition. The molecular weight of the product, i.e. polyethylene, varied from 397,000 to 988,000. 13C NMR study of the polymers indicate that fraction of branches and end groups percentage range from 0.01 to 0.55. X-ray diffraction analysis showed that polyethylene samples had highly crystalline structure within the orthorhombic space group (Pnam) and carbon–carbon interatomic distance of 0.154061 nm and the C–C–C angle of 112.192°.
Keywords: Polyethylene; Zirconium; Single site catalysts

Catalysis using colloidal-supported gold-based nanoparticles by Nikolaos Dimitratos; Ceri Hammond; Christopher J. Kiely; Graham J. Hutchings (85-94).
The discovery of novel m aterials that can be active, selective and stable catalysts for the efficient transformation of organic molecules to useful products is of high importance. In recent years, there has been significant interest in the utilisation of supported gold-based nanoparticles that can be effective catalysts for a broad range of chemical processes. In this paper, we describe and discuss the utilisation of gold-based nanoparticles as efficient catalysts for a range of important reactions, with particular emphasis placed on our team recent research.
Keywords: Gold catalysis; Nanoparticles; Alkane activation; Alcohol oxidation

The catalytic stability of some selected bifunctional nanoporous-based catalysts in the hydroisomerisation of n-C7 and the effect of post-synthesis modification techniques by Faisal M. Alotaibi; Raed H. Abudawood; Hamid A. Al-Megren; Mohammed C. Al-Kinany; Essam H. Jamea; Arthur A. Garforth (95-136).
In this work, some commercial and in-house nanoporous-based catalysts, such as USY, beta and mordenite zeolites, and mesoporous aluminosilicate molecular sieves such as MCM-48 and SBA-15, loaded with metals and acting as mono- and bimetallic bifunctional catalysts, were used for hydroisomerisation experiments in a fixed-bed reactor at pressures between 1 and 15 bar and at feed space time ranging from 2.57 to 10.26 h−1 (35.14–140.6 kg s mol−1) to hydroisomerise n-heptane over a temperature range of 210–270 °C. The effect of post-synthesis treatments of micro- and mesoporous catalysts was examined, regarding their activity, selectivity and stability, such as acid and steam dealumination techniques, acid leaching via a chelating agent, bimetal loading techniques, different platinum loading methods, and composite or hybrid catalyst generation. Results show that pore architecture is the most important factor affecting coke formation and deactivation in zeolite catalysts. It was found that those catalysts with high Si/Al ratios and those which had been acid-leached or steamed showed better activity, higher selectivity towards isomeric products and better time stability. Moreover, the balance between the number of metal sites and the number of acid sites played an important role in determining the activity, selectivity and stability of the bifunctional catalysts. Higher metal loading improves catalytic stability, due to a better balance and closeness of the catalytic functions. Moreover, the bimetallic catalyst improves the formation of smaller metal particles and better dispersion, which may affect selectivity and stability.
Keywords: The time-on-stream stability; Alkanes’ hydroisomerisation; Catalyst deactivation; Zeolites; Bifunctional catalysts; Nanoporous catalysts; Bimetallic catalysts

Dry reforming of methane over ZrO2-supported Co–Mo carbide catalyst by X. Du; L. J. France; V. L. Kuznetsov; T. Xiao; P. P. Edwards; Hamid AlMegren; Abdulaziz Bagabas (137-144).
The process of dry reforming of methane has the potential to be an effective route for CO2 utilization via syn-gas production. In the present study, ZrO2-supported Co–Mo bimetallic carbide catalysts were prepared via a co-precipitation method through a combined reduction and carburization procedure employing a CH4/H2 (20/80 %) mixture. All of the as-synthesized materials were tested at 850°, under atmospheric pressure and a CO2:CH4 ratio of 1. The importance of the ZrO2 support became immediately apparent when it exhibited a higher conversion than the corresponding low-surface-area bulk Mo2C catalyst, which we attribute to lewis acid and base active sites on the surface of ZrO2. From catalytic tests and pre-and post-reaction X-ray diffraction (XRD) patterns, we observed that different dispersions of the monometallic carbides, caused by varying the pre-heating temperatures on ZrO2, did not significantly affect conversion or yield. In contrast, incorporation of cobalt atoms into the Mo2C lattice significantly enhanced the conversion, yield and stability of the catalysts. Post-reaction XRD patterns indicated that the bimetallic carbide had enhanced the resistance to the oxidation effect that is known to deactivate Mo2C catalysts. In addition, increasing the Co loading in the mixed metal carbides was seen to enhance the resistance of the catalyst to the reverse water gas shift reaction, leading to improved stability of the H2 yields.
Keywords: Dry reforming of methane; Synthesis gas; Bimetallic carbide; Zirconia support

The effect of lanthanum addition on the catalytic activity of γ-alumina supported bimetallic Co–Mo carbides for dry methane reforming by Liam J. France; Xian Du; Naif Almuqati; Vladimir L. Kuznetsov; Yongxiang Zhao; Jiang Zheng; Tiancun Xiao; Abdulaziz Bagabas; Hamid Almegren; Peter P. Edwards (145-156).
The effect of lanthanum addition to γ-alumina supported bimetallic carbides has been studied for the reaction of dry methane reforming using four different lanthanum loading levels of 1, 5, 10 and 15 wt% of lanthanum. It has been demonstrated that the addition of lanthanum to supported bimetallic carbides at low loading levels (1 wt%) results in smaller carbide crystallite sizes compared to catalysts containing either no lanthanum or higher lanthanum loading levels (5–15 wt%). Increased lanthanum loading results in increased carbon dioxide desorption at 500–700 °C. Reactions indicated that increased lanthanum loading resulted in significantly reduced product yields due to increased reverse water–gas shift activity. All materials exhibited degrees of sintering during the reaction. It was found that cobalt reacted with lanthanum species to form a LaCoO3 phase. The 1 wt% catalyst possessed superior catalytic properties for dry methane reforming and was tested for 100 h. After an initial loss of activity, the catalyst appeared to stabilise, however, a decrease of ~3 % in the H2:CO ratio, evidence of carbide crystallite growth and carbon deposition, indicated that a shift in the side reactions had occurred during the reaction.
Keywords: Dry methane reforming; Bimetallic carbide; Lanthanum; Carbon dioxide

The feedstock curve: novel fuel resources, environmental conservation, the force of economics and the renewed east–west power struggle by Oliver R. Inderwildi; Fabian Siegrist; Robert Duane Dickson; Andrew J. Hagan (157-165).
Rapid technological advancements can make previously uneconomic resources and/or feedstock available within significantly reduced timeframes. This can and will further transform the global energy landscape and moreover, will impact the mix of feedstock we use for energy provision and material production—the so-called Feedstock Curve. Herein, three current examples are assessed to illustrate that this restructuring has by far wider reaching implications: Firstly, we examine how unconventional resources—mainly produced using fractured cracking techniques—have restructured the US energy landscape, are now fueling the US economic recovery and will impact the geopolitical balance. Secondly, we assess how unconventional resources could impact European energy security, the Crimean crisis and redirect global cash flows. Thirdly, we analyse the potential impact of so-called methane hydrates deposited off the shores of Japan on the energy transition of the Island nation and how they might impact its trade deficit and long-term economic outlook. Last but not least, we will present arguments that unconventional resources, when regulated properly, may be a blessing for the environment. With these examples, this think piece and concept note will illustrate the interconnectedness of economics, politics, environmental conservation and technology.
Keywords: Energy security; Foreign policy; International security; Resources; Global change