Hydrotreating of tall oils on a sulfided NiMo catalyst for the production of base-chemicals in steam crackers

Development of new and innovative products through efficient technologies is essential for the implementation of sustainable developments in highly competitive chemical industries. Based on this context, raw materials originating from biomass have been widely used for the production of chemicals and materials. Steam cracking of bio-based or renewable feedstocks in a conventional steam cracking set-up is identified as a promising approach for the sustainable production of base-chemicals. In a two-step process for the production of base-chemicals, firstly, bio-derived feedstock is upgraded into a more suitable feedstock which comprises mainly paraffin range hydrocarbons with a lower oxygen content than the original feedstock; secondly, the upgraded feedstock is converted into base-chemicals by conventional steam cracking technology. This research work identifies wood-derived tall oil as a potential feedstock for the production of base-chemicals by catalytic upgrading and steam cracking methods. The main aim of this work was to carry out the catalytic hydrotreating of tall oil feedstocks such as tall oil fatty acid (TOFA), distilled tall oil (DTO) and crude tall oil (CTO) on a commercial, sulfided NiMo catalyst at different process conditions. The effects of space time and process temperatures on the distribution of products from the hydrotreatment of different tall oil feeds were investigated. Hydrotreating chemistry of oxygenates in tall oil were assessed based on the achieved conversion of reactants and product distribution under the investigated conditions. Furthermore, the steam cracking of hydrodeoxygented tall oil (HDO-tall oil) feeds was carried out, and evaluation of the yield of olefins in comparison with conventional steam cracking feeds such as naphtha and natural gas condensate (NGC)

Bio-ethylene production: alternatives for green chemicals and polymers

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Artificial intelligence in steam cracking modeling : a deep learning algorithm for detailed effluent prediction

Chemical processes can benefit tremendously from fast and accurate effluent composition prediction for plant design, control, and optimization. The Industry 4.0 revolution claims that by introducing machine learning into these fields, substantial economic and environmental gains can be achieved. The bottleneck for high-frequency optimization and process control is often the time necessary to perform the required detailed analyses of, for example, feed and product. To resolve these issues, a framework of four deep learning artificial neural networks (DL ANNs) has been developed for the largest chemicals production process-steam cracking. The proposed methodology allows both a detailed characterization of a naphtha feedstock and a detailed composition of the steam cracker effluent to be determined, based on a limited number of commercial naphtha indices and rapidly accessible process characteristics. The detailed characterization of a naphtha is predicted from three points on the boiling curve and paraffins, iso-paraffins, olefins, naphthenes, and aronatics (PIONA) characterization. If unavailable, the boiling points are also estimated. Even with estimated boiling points, the developed DL ANN outperforms several established methods such as maximization of Shannon entropy and traditional ANNs. For feedstock reconstruction, a mean absolute error (MAE) of 0.3 wt% is achieved on the test set, while the MAE of the effluent prediction is 0.1 wt%. When combining all networks-using the output of the previous as input to the next-the effluent MAE increases to 0.19 wt%. In addition to the high accuracy of the networks, a major benefit is the negligible computational cost required to obtain the predictions. On a standard Intel i7 processor, predictions are made in the order of milliseconds. Commercial software such as COILSIM1D performs slightly better in terms of accuracy, but the required central processing unit time per reaction is in the order of seconds. This tremendous speed-up and minimal accuracy loss make the presented framework highly suitable for the continuous monitoring of difficult-to-access process parameters and for the envisioned, high-frequency real-time optimization (RTO) strategy or process control. Nevertheless, the lack of a fundamental basis implies that fundamental understanding is almost completely lost, which is not always well-accepted by the engineering community. In addition, the performance of the developed networks drops significantly for naphthas that are highly dissimilar to those in the training set. (C) 2019 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company

Analysis of process variables via CFD to evaluate the performance of a FCC riser

Feedstock conversion and yield products are studied through a 3D model simulating the main reactor of the fluid catalytic cracking (FCC) process. Computational fluid dynamic (CFD) is used with Eulerian-Eulerian approach to predict the fluid catalytic cracking behavior. The model considers 12 lumps with catalyst deactivation by coke and poisoning by alkaline nitrides and polycyclic aromatic adsorption to estimate the kinetic behavior which, starting from a given feedstock, produces several cracking products. Different feedstock compositions are considered. The model is compared with sampling data at industrial operation conditions. The simulation model is able to represent accurately the products behavior for the different operating conditions considered. All the conditions considered were solved using a solver ANSYS CFX 14.0. The different operation process variables and hydrodynamic effects of the industrial riser of a fluid catalytic cracking (FCC) are evaluated. Predictions from the model are shown and comparison with experimental conversion and yields products are presented; recommendations are drawn to establish the conditions to obtain higher product yields in the industrial process

Catalytic coatings on steel for low-temperature propane prereforming to solid oxide fuel cell (SOFC) application

Catalyst layers (4–20 lm) of rhodium (1 wt%) supported on alumina, titania, and ceria–zirconia (Ce0.5Zr0.5O2) were coated on stainless-steel corrugated sheets by dip-coating in very stable colloidal dispersions of nanoparticles in water. Catalytic performances were studied for low-temperature (6500 C) steam reforming of propane at a steam to carbon ratio equal to 3 and low contact time (0.01 s). The best catalytic activity for propane steam reforming was observed for titania and ceria–zirconia supports for which propane conversion started at 250 C and was more than three times better at 350 C than conversion measured on alumina catalyst. For all catalysts a first-order kinetics was found with respect to propane at 500 C. Addition of PEG 2000 in titania and ceria–zirconia sols eliminated the film cracking observed without additive with these supports. Besides, the PEG addition strongly expanded the porosity of the layers, so that full catalytic efficiency was maintained when the thickness of the ceria–zirconia and titania films was increased

Thermogravimetric kinetics of crude glycerol.

The pyrolysis of the crude glycerol from a biodiesel production plant was investigated by thermogravimetry coupled with Fourier transform infrared spectroscopy. The main gaseous products are discussed, and the thermogravimetric kinetics derived. There were four distinct phases in the pyrolysis process of the crude glycerol. The presence of water and methanol in the crude glycerol and responsible for the first decomposition phase, were shown to catalyse glycerol decomposition (second phase). Unlike the pure compound, crude glycerol decomposition below 500 K leaves behind a large mass fraction of pyrolysis residues (ca. 15%), which eventually partially eliminate in two phases upon reaching significantly higher temperatures (700 and 970 K, respectively). An improved iterative Coats-Redfern method was used to evaluate non-isothermal kinetic parameters in each phase. The latter were then utilised to model the decomposition behaviour in non-isothermal conditions. The power law model (first order) predicted accurately the main (second) and third phases in the pyrolysis of the crude glycerol. Differences of 10-30 kJ/mol in activation energies between crude and pure glycerol in their main decomposition phase corroborated the catalytic effect of water and methanol in the crude pyrolysis. The 3-D diffusion model more accurately reproduced the fourth (last) phase, whereas the short initial decomposition phase was poorly simulated despite correlation coefficients ca. 0.95-0.96. The kinetics of the 3rd and 4th decomposition phases, attributed to fatty acid methyl esters cracking and pyrolysis tarry residues, were sensitive to the heating rate

Optimization of Charcoal Production Process from Woody Biomass Waste: Effect of Ni-Containing Catalysts on Pyrolysis Vapors

Woody biomass waste (Pinus radiata) coming from forestry activities has been pyrolyzed with the aim of obtaining charcoal and, at the same time, a hydrogen-rich gas fraction. The pyrolysis has been carried out in a laboratory scale continuous screw reactor, where carbonization takes place, connected to a vapor treatment reactor, at which the carbonization vapors are thermo-catalytically treated. Different peak temperatures have been studied in the carbonization process (500-900 degrees C), while the presence of different Ni-containing catalysts in the vapor treatment has been analyzed. Low temperature pyrolysis produces high liquid and solid yields, however, increasing the temperature progressively up to 900 degrees C drastically increases gas yield. The amount of nickel affects the vapors treatment phase, enhancing even further the production of interesting products such as hydrogen and reducing the generated liquids to very low yields. The gases obtained at very high temperatures (700-900 degrees C) in the presence of Ni-containing catalysts are rich in H-2 and CO, which makes them valuable for energy production, as hydrogen source, producer gas or reducing agent.The authors thank the Basque Country Government (consolidated research groups funding and Programa predoctoral de formacion de personal investigador no doctor), Befesa Steel R&D company for financial assistance for this work and Biotermiak Zeberio 2009 S.L. for the supply of fresh biomass

Influence of the catalyst support on the steam reforming performance of toluene as tar model compound

The large amount of tar produced along with the syngas during biomass gasification is one of the major obstacle for the diffusion of gasifiers at industrial scale. Catalytic cracking and reforming are the most suitable processes for the transformation of tar into lighter gases. The selection of suitable catalysts is a critical step. The catalysts must own high activity and high resistance to deactivation for coke deposition. In this work the effect of two different supports, mayenite and aluminium oxide, on the activity of the nickel was investigated in the steam reforming of toluene that was used as tar model compound. In particular, the performed experimentations aimed to test the mayenite in terms of improvement of resistance to carbon deposition in conditions similar to those of gasification reactors. The obtained results indicate that Ni /mayenite catalyst needs higher temperature to activate and leads to lower value of toluene conversion with respect to Ni / alumina. However, mayenite, which is known from literature to have higher resistance to coke deposition due to the presence of free oxygens in the lattice which oxidize the coke deposited on the catalyst surface showed higher resistance to deactivation especially for low steam to carbon ratios

Gasification of Pine Wood Chips with Air-Steam in Fluidized Bed

Tato práce studovala vliv použití vzduchu a páry jako zplynovacího činidla ve zkapalňovacím generátoru plynu na vlastnosti vyprodukovaného plynu (oxid uhelnatý, vodík, obsah dehtu a nízká výhřevnost). Tato studie byla založena na experimentech které byly provedeny ve fluidním generátoru plynu Biofluid 100 v laboratoři Energetického ústavu technologické univerzity Brno s použitím páry jako zplynovacího činidla a borovicového dřeva jako výchozí suroviny. Cílem této dizertační práce je stanovit nejlepší provozní parametry systému při užití vodní páry a vzduchu ve zplynovacím zařízení biofluid 100, při kterých se dosáhne nejvyšší kvality plynu. K dosažení tohoto cíle bylo provedeno mnoho experimentů studujících účinky teploty reaktoru(T101), poměru páry a biomasy (S/B) poměru páry a vzduchu (S/A), teploty dodávané páry (Tf1), ekvivalentního poměru ER,ve složení vyprodukovaném plynu, výhřevnost, výtěžnost plynu, efektivnost přeměny uhlíku a účinnost zplynovače. Výsledky experimentů ukázaly, že zvýšení teploty reaktoru vede ke zvýšení obsahu vodíku a oxidu uhelnatého, výhřevnosti, výtěžnosti plynu, efektivnosti přeměny uhlíku, efektivnosti zplynovače a ke snížení obsahu dehtu. Příliš vysoká teplota reaktoru ale snižuje výhřevnost plynu. Dodáváním páry se zvýšila kvalita plynu, vyšší H_2,LHV a nižší obsah dehtu. Přesto ale nadměrné množství páry snižuje zplyňovací teplotu a tím i kvalitu plynu. Poměr páry a biomasy při kterém se dosáhne nejlepší kvality plynu se zvýší s teplotou reaktoru. Bylo zjištěno, že kdykoli byla teplota páry (Tf1) vyšší, byl plyn více kvalitní, ale zvyšování teploty páry také zvyšuje ekonomické náklady na vyprodukovaný plyn což se při masové produkci plynu musí brát v úvahu. Efekt ekvivalentního poměru ER, byl studován postupným zvyšováním, bylo zjištěno, že nejlepší ekvivalentní poměr pro dosažení nejvyšší kvality plynu byl kolem 0.29, při ER > 0.29 byl obsah hořlavého plynu snížen a to vedlo ke snížení kvality plynu. Obsah dehtu se snižuje jak zvýšením teploty reaktoru tak poměrem páry k biomase. Podle výsledků experimentů a diskuze, bylo zjištěno, že při použití směsi páry a vzduchu se kvalita plynu zvýší, parametry pro dosažení nejvyšší kvality vyprodukovaného plynu při experimentálních podmínkách jsou: T101 =829 S/B=0.67((kg steam)/(kg biomass)) ,S/A=0.67((kg steam)/(kg air)) , ER= 0.29 and a Tf1 je nejvyšší možná teplota,při které se vodík zvýší z 10.48 na 19,68% a výhřevnost z 3.99 na 5.52(MJ/m^3 ) a obsah dehtu z 1964(mg/m^3 ) na 1046(mg/m^3 ) zvýšením z 0 na 0.67 při T101=829 .This work has been studied the impact of using of air-steam as gasification agent in fluidized bed gasifier on produced gas properties (Carbon monoxide, Hydrogen,tar content and low heating value . This study has been based on the experiments which have been done in fluidized bed gasifier called Biofluid 100, where exists in lab of the Institute of Power Engineering, Brno University of Technology, by using air-steam as agent of gasifier and pine wood chips as the feedstock. The aim of this thesis is to determine the best operating parameters of system air- steam gasification in biofloud 100 which achive the best gas quality. To accomplish this task , many experiments have been performed to studied the effect of reactor temperature(T101), steam to biomass ratio (S/B), steam to air ratio (S/A) , temperature of provided steam (Tf1) and equivalence ratio (ER)on produced gas composition , low heating value(LHV),gas yield ,carbon conversion efficiency and gasifier efficiency. The results of experiments have been shown , that the increase the temperature of reactor (T101) lead to increase hydrogen content , carbon monoxide content ,low heating value,gas yield , carbon conversion efficiency ,gasifier efficiency and reduce the tar content, but too high reactor temperature lowered low heating value of gas. By providing steam,the gas quality (H_2,LHVand tar content) has been imroved ,however excessive steam has been lowered gasification temperature and thus reduced gas quality. The ratio of steam to biomass, which achieve the best gas quality has been increased by reactor temperature. It has been found, that whenever steam temperature (Tf1)was higher , whenever the gas produced more quality, but the increase of steam temperature will increase the economic cost of the product gas,which must take into account when gas production widely. The effect of equivalence ratio(ER) has been studied with increase S/B , it has been found that the best value of equivalence ratio was around 0.29 which achieved the best quality of produced gas , where when ER > 0.29 the combustible gases content have been decreased so it led to lower the gas quality . Tar content decreases by increasing each of reactor temperature (T101) and steam to biomass ratio . According to the results of the experiments and discussion, it has been found, that by using the mixture of steam and air ,the gas quality will be improved ,and the parameters, which will achieve the best quality of the produced gas at experimental conditions are: T101 =829 S/B=0.67((kg steam)/(kg biomass)) ,S/A=0.57((kg steam)/(kg air)) , ER= 0.29 and Tf1 is the highest possible temperature, where hydrogen increased from 10.48 to 19,68 % and Low heating value from 3.99 to 5.52(MJ/m^3 ) and tar decreased from 1964 to 1046 (mg/m^3 ) by increasing S/B from 0 to 0.67 at T101=829 .