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Öğe Activated carbons from co-carbonization of waste truck tires and spent tea leaves(Elsevier, 2021) Guclu, Cansu; Alper, Koray; Erdem, Murat; Tekin, Kubilay; Karagoz, SelhanThis study reports the co-carbonization of waste truck tires (WTT) and spent tea leaves (STL) at different blend ratios using chemical activating reagents (KOH and ZnCl2) carried out at 800 C. The highest BET surface area from blends was 527.24 m2/g, obtained using ZnCl2 activation at a blend ratio of 1:3 (WTT/STL). Activated carbons yields in the blends were the highest at a blend ratio of 3:1 (WTT/STL) for both chemical activations. They were 24.37 wt% for KOH activation and 41.59 wt% for ZnCl2 activation. ZnCl2 activation produced higher carbon and lower oxygen content than those using KOH activation. Regardless of the type of feed, the oxygen removal efficiency of ZnCl2 was higher than that of KOH under identical conditions. Among all the activated carbons produced, the BET surface area of the activated carbons obtained from the carbonization of STL alone was highest for both activations. The BET surface area of the activated carbons produced in this study was comparable to that of activated carbons produced commercially.Öğe Activated carbons from co-carbonization of waste truck tires and spent tea leaves (vol 21, 100410, 2021)(Elsevier, 2021) Guclu, Cansu; Alper, Koray; Erdem, Murat; Tekin, Kubilay; Karagoz, Selhan[No abstract available]Öğe Atık lignoselülozik biyokütlenin su ve etanol içerisinde katalitik sıvılaştırılması(Karabük Üniversitesi, 2019) Alper, Koray; Tekin, Kubilay21. yüzyılda, fosil kaynakların daha sürdürülebilir alternatif kaynaklarla değiştirilmesi en büyük zorluklardan biridir. Lignoselülozik biyokütle, çevre dostu ve yenilenebilir olmak, yaygın olarak bulunmak gibi temel kriterlere sahip az sayıda kaynaktan biridir ve petrolün aksine oksijen oranı yüksek, katı ve heterojen bir maddedir. Bu nedenle, yakıtlara ve değerli kimyasallara dönüşümü için verimli süreçler geliştirmek çok önemlidir. Su ve etanol, lignoselülozik biyokütlenin dönüşümü için yaygın olarak kullanılan reaksiyon ortamlarıdır. Bu çalışmada, lignoselülozik biyokütle (meşe talaşı, ladin talaşı, göknar talaşı ve üzüm çekirdeği) su ve etanol içerisinde katalizörsüz ve katalizörlü (ZSM-5, MgCl2:TiCl4, KF/Al2O3, Pd/C, Sm(OTf)3, La(OTf)3, Cu(OTf)2) ortamda sıvılaştırılmıştır. Deneyler 250, 300 ve 350°C sıcaklıklarda ve 15, 30 ve 60 dakika reaksiyon sürelerinde gerçekleştirilmiştir. Katalizörlerin ürün (biyo-yağ ve katı ürün) verimine ve içeriğine etkisi incelenmiştir. Katı ürünlerin karakterizasyonu için taramalı elektron mikroskobu (SEM) ve elementel analiz cihazları kullanılmıştır. Biyo-yağların analizi için GC-MS (gaz kromatografisi-kütle spektrometresi), elementel analiz ve termogravimetrik analiz (TGA) cihazları kullanılmıştır.Öğe Co-hydrothermal Liquefaction of Lignocellulosic Biomass with Kukersite Oil Shale(Amer Chemical Soc, 2019) Akalin, Ece; Kim, Young-Min; Alper, Koray; Oja, Vahur; Tekin, Kubilay; Durukan, Ilknur; Siddiqui, Muhammad ZainThe co-hydrothermal liquefaction of black pine wood (BPW) with Kukersite oil shale (KOS) at different blend ratios of BPW/KOS (1:1, 1:2, and 2:1) was conducted at 300 degrees C for 30 min. No synergistic effects on oil yields from the co-hydrothermal processing have been observed. However, when the methanol was substituted with hot compressed water as the solvent, positive synergistic effects on the oil yields were observed for all blend ratios, but the heating values of the oils from hydrothermal processing were higher than those from supercritical methanol processing under identical conditions. Co-hydrothermal liquefaction of BPW with KOS produced oils with less oxygen than those from co-supercritical methanol processing of BPW with KOS under identical conditions. The highest heating value from co-processing was 30.22 MJ/kg, which was obtained from the co-hydrothermal liquefaction of BPW with KOS at a blend ratio of 1:2. Oils from the co-hydrothermal liquefaction of BPW with KOS contained phenols, acids, ketones, and aldehydes. Guaiacol was the primary compound detected in the oils from co-hydrothermal processing. The relative yield of this compound was highest at a blend ratio of 1:2 (BPW/KOS). The prominent compounds in oils from the co-supercritical methanol processing were esters and phenols.Öğe Comparative studies of hydrochars and biochars produced from lignocellulosic biomass via hydrothermal carbonization, torrefaction and pyrolysis(Elsevier Sci Ltd, 2023) Ercan, Betul; Alper, Koray; Ucar, Suat; Karagoz, SelhanIn this study, hydrothermal carbonization, torrefaction, and pyrolysis of hornbeam wood chips were performed. Different runs were conducted at varying temperatures ranging from 225 to 575 & DEG;C, and the resulting biochars and hydrochars were analyzed. Biochars obtained from torrefaction runs had high yields, but no significant structural changes compared to raw material. Biochars produced from pyrolysis runs had high fixed carbon content that increased with temperature. Hydrochars obtained from hydrothermal carbonization had higher degree of carbonization than biochars produced from torrefaction under identical conditions. The order of carbonization degree, from highest to lowest, was: biochars obtained from the pyrolysis process, hydrochars produced from the hydrothermal carbonization process, and biochars obtained from the torrefaction process. The highest heating value of the biochar was 32.51 MJ kg-1, produced from the pyrolysis run at 575 & DEG;C.Öğe Deconstruction of lignocellulosic biomass with hydrated cerium (III) chloride in water and ethanol(Elsevier Science Bv, 2017) Akalin, Mehmet K.; Das, Parthapratim; Alper, Koray; Tekin, Kubilay; Ragauskas, Arthur J.; Karagoz, SelhanLignocellulosic biomass was decomposed to produce crude bio-oil in water and ethanol using hydrated cerium (III) chloride as a catalyst. Use of the catalyst affected not only the yield of crude bio-oil but also the composition of bio-crude for both water and ethanol. The catalyst had a detrimental effect on the crude bio-oil yields obtained from water processing for all runs. However, in ethanol, use of the catalyst improved the crude bio-oil yields in all tested runs. The solid residue yields decreased with the catalyst use in the runs with water but increased in all studies with ethanol, except those with the shortest tested residence time of 10 min. The highest crude bio-oil yield of 48.2 wt% was obtained at 300 degrees C using 5 mmol of hydrated cerium (III) chloride at a residence time of 90 min in ethanol. The heating values of the crude bio-oils increased with the catalyst use for both water and ethanol processing. The highest heating value of 33.3 MJ kg(-1) was obtained with hydrated cerium (III) chloride at 300 degrees C and a residence time of 120 min.Öğe Effects of hydrothermal carbonization on products from fast pyrolysis of cellulose(Elsevier Sci Ltd, 2021) Guducu, Isa; Alper, Koray; Evcil, Tolgahan; Tekin, Kubilay; Ohtani, Hajime; Karago, SelhanIn the first step of this study, the hydrothermal carbonization (HTC) of cellulose was performed at 225 and 250 degrees C for 4, 8 and 12 h. The effect of temperature and residence time on hydrochar (HC) yields and characteristics was investigated, and the highest hydrochar yield had a heating value of 21.06 MJ/kg. In the second step, cellulose and hydrochar-derived cellulose was subjected to fast online pyrolysis at 500, 600 and 700 degrees C, using a pyrolysis-gas chromatography-mass spectrometry system. The HTC process significantly affected the pyrolysis products. The major decomposition product resulting from the fast pyrolysis of cellulose was levoglucosan, but at all tested temperatures, 2-methylfuran was the major product from hydrochars. Increasing the pyrolysis temperature caused a decrease in the relative yield of 2-methylfuran. Another prominent compound observed in pyrolyzates was 2,5-dimethylfuran. The relative yields of these two compounds decreased when the residence time of the HTC process was increased. The highest 2-methylfuran selectivity was 67.4%, while the highest 2,5-dimethylfuran selectivity among the furanic compounds was 24.0%. This study demonstrated that, by combining HTC and pyrolysis processes, fine chemicals can be produced from cellulose.Öğe Hydrothermal and supercritical ethanol processing of woody biomass with a high-silica zeolite catalyst(Springer Heidelberg, 2019) Alper, Koray; Tekin, Kubilay; Karagoz, SelhanThe effects of high-silica ZSM-5 on the yields, as well as compositions, of bio-oil and solid residue obtained from oak wood sawdust were investigated. The catalyst, in concentrations from 5 to 40 wt% of the raw lignocellulose material, was tested in hydrothermal (HT) and supercritical ethanol (SCE) media. The highest bio-oil yields were 11.0 and 32.4 wt% for HT and SCE processing, respectively, and were obtained by using 20 wt% ZSM-5. After the noncatalytic and catalytic HT processing and noncatalytic SCE processing of lignocellulose, the major products were phenols, whereas esters were the major products in the bio-oils obtained from the catalytic SCE processing of oak wood sawdust. The use of ZSM-5 increased the relative contents of the ester compounds in the bio-oils from the SCE processing, while the catalyst did not significantly change the composition of the bio-oils produced from the HT processing of oak wood sawdust. The highest heating values of the bio-oils were 27.11 and 25.65 MJ kg(-1) for HT and SCE processing, respectively, and were obtained from the noncatalytic runs. The amount of recovered carbon in the bio-oils from the catalytic runs was higher than that from the noncatalytic runs for both HT and SCE processing. The carbon content of the solid residues for both HT and SCE processing decreased with the use of a catalyst. An increase in the catalyst concentration led to a decrease in the carbon content of the solid residues in SCE and HT processing.Öğe Hydrothermal Liquefaction of Lignocellulosic Biomass Using Potassium Fluoride-Doped Alumina(Amer Chemical Soc, 2019) Alper, Koray; Tekin, Kubilay; Karagoz, SelhanHydrothermal liquefaction (HTL) of spruce wood was performed without and with the use of a potassium fluoride-doped alumina catalyst (KF/Al2O3) in a bench-top reactor. HTL runs were performed at 250, 300, and 350 degrees C with residence times of 15, 30, and 60 min. The effects of the catalyst at different catalyst loadings (in concentrations from 10 to 40 wt % of the lignocellulosic biomass) on the bio-oil and solid residue yields as well as their properties were investigated. The use of the catalyst increased the bio-oil yields over twofold and reduced char yields. Gas chromatography-mass spectrometry analysis revealed that the bio-oil from the noncatalytic and catalytic runs consisted of aldehydes, ketones, phenols, acids, and esters. Among these components, phenolic compounds were dominant in both the noncatalytic and catalytic runs. The relative yields of phenolic compounds increased with catalyst use. The highest heating value was estimated to be approximately 29 MJ/kg. The boiling point distributions of the bio-oils from both runs revealed that the total naphtha fraction (light and heavy) was comparable to that of crude oil.Öğe One-pot transformation of lignocellulosic biomass into crude bio-oil with metal chloride catalyst via hydrothermal and supercritical ethanol processing(Amer Chemical Soc, 2019) Hao, Naijia; Ragauskas, Arthur; Alper, Koray; Karagoz, Selhan; Tekin, Kubilay[No abstract available]Öğe One-pot transformation of lignocellulosic biomass into crude bio-oil with metal chlorides via hydrothermal and supercritical ethanol processing(Elsevier Sci Ltd, 2019) Hao, Naijia; Alper, Koray; Tekin, Kubilay; Karagoz, Selhan; Ragauskas, Arthur J.Grape seeds were deconstructed in both hydrothermal and supercritical ethanol media with a combination of two metal chlorides (TiCl4:MgCl2) to produce bio-oils. The use of metal chloride additives in supercritical ethanol achieved the highest bio-oil yield of 49.2 wt% (300 degrees C, 30 min). Both the hydrothermal and supercritical ethanol deconstruction with the additives (TiCl4:MgCl2 = 4 mmol:4mmol) produced the bio-oils with a higher heating value (HHV) of 35 MJ/Kg. Gas chromatography-mass spectrometry (GC-MS) analysis of the bio-oils showed that the major products in bio-oils from the hydrothermal deconstruction were acids while the majority products in bio-oils form the supercritical ethanol deconstruction were esters. Nuclear magnetic resonance (NMR) data of the bio-oils suggested that both hydrothermal and supercritical ethanol deconstruction with metal chlorides significantly reduced the non-condensed OH and oxygenated lignin sub-units in bio-oils; while only supercritical ethanol deconstruction with metal chlorides reduced the aliphatic OH and O-alkylated structures in bio-oils.Öğe One-step transformation of biomass to fuel precursors using a bi-functional combination of Pd/C and water tolerant Lewis acid(Elsevier Sci Ltd, 2020) Hao, Naijia; Alper, Koray; Patel, Himanshu; Tekin, Kubilay; Karagoz, Selhan; Ragauskas, Arthur J.Direct one-pot transformation of lignocellulosic biomass has been developed as an effective and sustainable strategy to produce fuel blend stocks and high value chemical building blocks. In this wok, a bi-functional catalyst system consisting of palladium supported on carbon (Pd/C) and metal triflates (i.e., Sm(OTf)(3), La(OTf)(3), and Cu(OTf)(3) were shown to promote the biomass liquefaction in both hot-compressed water and supercritical ethanol medium, converting fir wood into oxygenated compounds. The highest bio-oil yield from hydrothermal liquefaction (HTL) was 10.47 wt% over Pd/C whereas the highest bio-oil yield of 49.71 wt% was achieved from supercritical ethanol liquefaction (SCEL) over the bi-functional catalyst system of Pd/C and La(OTf)(3). Higher heating values, carbon recovered values and boiling point distributions were further determined for elucidating the physical properties of the bio-oils. Gas chromatography mass spectrometry (GC-MS) analysis of the bio-oils revealed the chemical composition of the bio-oils. Substituted phenols and cyclopentenone/cyclopentanone type compounds consisted of more than 60 area% of the total products from HTL, whereas phenol and esters represented the major products from SCEL. The major reaction pathways are proposed based on the GC-MS results, which include depolymerizaton, isomerization, dehydration, condensation, and hydrogenation.Öğe Pyrolysis of agricultural residues for bio-oil production(Springer, 2015) Alper, Koray; Tekin, Kubilay; Karagoz, SelhanThe production of biofuel from biomass waste is of great interest to the scientific community regarding the discovery of solutions to global energy demand and global warming. The pyrolysis of biomass to produce bio-oil is an easy, cheap and promising technology. In the current investigation, the pyrolysis of two different biomasses (cornelian cherry stones and grape seeds) was achieved at temperatures ranging from 300 to 700 A degrees C. The effect of pyrolysis temperatures on the yields of each product was significant. The bio-oil yields were maximized at 500 A degrees C for cornelian cherry stones and 700 A degrees C for grape seeds. The compositions of bio-oils for both cornelian cherry stones and grape seeds were similar and contained mainly oxygenated hydrocarbons. The compounds observed in this investigation were composed of phenols, alkyl benzenes, alkanes, alkenes, fatty acids, fatty acid esters and a few nitrogen-containing compounds. Bio-char properties were amended in association with both the pyrolysis temperature and biomass type. Bio-chars from cornelian cherry stones contained higher carbon and lower oxygen levels than those from grape seeds under identical conditions. Increases in pyrolysis temperatures produced bio-chars containing higher carbon levels and heating values for both carnelian cherry stones and grape seeds.Öğe Pyrolysis of Date palm waste in a fixed-bed reactor: Characterization of pyrolytic products(Elsevier Sci Ltd, 2018) Bensidhom, Gmar; Ben Hassen-Trabelsi, Aida; Alper, Koray; Sghairoun, Maher; Zaafouri, Kaouther; Trabelsi, IsmailThe pyrolysis of several Tunisian Date Palm Wastes (DPW): Date Palm Rachis (DPR), Date Palm Leaflets (DPL), Empty Fruit Bunches (EFB) and Date Palm Glaich (DPG) was run using a fixed-bed reactor, from room temperature to 500 degrees C, with 15 degrees C/min as heating rate and -5 degrees C as condensation temperature, in order to produce bio-oil, biochar and syngas. In these conditions, the bio-oil yield ranges from 17.03 wt% for DPL to 25.99 wt% for EFB. For the biochar, the highest yield (36.66 wt%) was obtained for DPL and the lowest one (31.66 wt%) was obtained from DPG while the syngas production varies from 39.10 wt% for DPR to 46.31 wt% DPL. The raw material and pyrolysis products have been characterized using elemental analysis thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). The syngas composition has been characterized using gas analyzer.Öğe Pyrolysis of Tunisian Date Palm Residues for the Production and Characterization of Bio-Oil, Bio-Char and Syngas(Springer International Publishing Ag, 2018) Bensidhom, Gmar; Ben Hassen-Trabelsi, Aida; Sghairoun, Maher; Alper, Koray; Trabelsi, Ismail[No abstract available]Öğe Sulfonic Acid-Catalyzed Biocoal Production from Lignocellulosic Biomass(Amer Chemical Soc, 2024) Alper, Koray; Auersvald, Milos; Kejla, Lukas; Ercan, Betul; Ucar, Suat; Tekin, Kubilay; Simacek, PavelIn this study, hydrothermal carbonization (HTC) of spruce wood was studied at different temperatures (200-260 degrees C) and residence times (2-48 h). An increase in the temperature and residence time resulted in higher heating values of hydrochars. The effect of temperature on the hydrochar yield and carbon content was more pronounced than the residence time. Two sulfonic acid catalysts were explored for the first time in the HTC of spruce wood at 240 degrees C for 24 h. The impact of sulfonic acid type and concentration on hydrochar yields and characteristics was investigated. Among the tested acids, methanesulfonic acid (MSA) had a significant effect on HTC, producing hydrochar with increased fixed carbon content and a higher heating value compared to noncatalytic runs and runs with dodecyl benzenesulfonic acid (DBSA) under identical conditions. The highest fuel ratio obtained was 1.47 with MSA at a concentration of 0.01 M. A detailed quantitative analysis of the aqueous phase from HTC processing using gas chromatography helped to elucidate the differences between the tested acids and demonstrated promoted lignin depolymerization with increasing MSA concentration. The use of sulfonic acid significantly increased the yield of levulinic acid in the aqueous phase. Overall, these findings highlight the potential of sulfonic acid catalysts in enhancing the efficiency and product quality of HTC processes, providing insights into optimizing biomass conversion for sustainable energy production and biocoal synthesis.Öğe Sustainable energy and fuels from biomass: a review focusing on hydrothermal biomass processing(Royal Soc Chemistry, 2020) Alper, Koray; Tekin, Kubilay; Karagoz, Selhan; Ragauskas, Arthur J.Fossil fuels are being replaced with renewable energy resources (biomass and biomass waste, solar, geothermal, wind,etc.) to ensure sustainable development, reduce the dependence on fossil fuels, address environmental challenges including climate change. Today, biomass produces 5 x 10(19)kJ of energy/year, which corresponds to 10% of the annual global energy consumption. Considering the variety of biomass resources, this value is predicted to reach 150 x 10(19)kJ by 2050. Biomass may become even more important for use as an energy resource and chemical raw material in the 21st century. Hydrothermal biomass conversion stands out as a promising and alternative technology. Methods such as traditional gasification and pyrolysis require dry biomass. Hydrothermal techniques have been developed to eliminate the cost and time required for drying biomass. The purpose of this process is to decompose biomass with a high moisture content into small molecules and reduce its oxygen content to obtain liquid fuels or valuable chemicals. This review presents the current and future state of energy, energy sources, biomass properties and biomass conversion technologies with a focus on hydrothermal technologies.Öğe Synthesis of bis[N-(p-aryl)-carbamoyloxy]alkanes as new low-molecular weight organogelators(Pergamon-Elsevier Science Ltd, 2015) Demir-Ordu, Oznur; Simsir, Hamza; Alper, KorayA series of bis-carbamate-based low-molecular-weight organogelators were synthesized, and their structure property relationships with respect to their gelation abilities in organic solvents were investigated. The self-aggregation behavior of the thermoreversible organogels was investigated by FTIR, temperature-dependent NMR, and SEM studies. The results revealed that the self-assembly into fibrous structures is driven by hydrogen bonding, it it stacking, and hydrophobic interactions. It was found that para-aryl substitution and the number of methylene units connecting two carbamate groups had a significant influence on gelation. The effect of temperature on gel formation was also investigated for all compounds. The most interesting feature was observed for p-hexyl derivative, which gels at -18 degrees C but not room temperature. Furthermore, thermal properties of the gels were studied by dropping ball experiments and DSC. para-Alkoxyphenyl derivatives were also found to be good organogelators for olive oil, sunflower oil, corn oil, and ethyl laurate, isopropyl myristate, n-butyl palmitate. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Use of a Lewis acid, a Bronsted acid, and their binary mixtures for the hydrothermal liquefaction of lignocellulose(Elsevier Sci Ltd, 2021) Alper, Koray; Wang, Yun-Yan; Meng, Xianzhi; Tekin, Kubilay; Karagoz, Selhan; Ragauskas, Arthur J.The main objective of the present study is to investigate the effect of a Lewis acid, Bronsted acid, and their combined use on the hydrothermal liquefaction of lignocellulosic biomass. Hydrothermal liquefaction of teak wood was conducted at 250, 300 and 350 degrees C for 15, 30 and 60 min. Hydrothermal liquefaction of teak wood was carried out at 300 degrees C for 30 min (the best optimum conditions) without and with the use of Mg(ClO4)(2), HClO4, and HClO4/Mg(ClO4)(2) at various loadings (2-10 mmol/15 g wood). The highest bio-oil yield was obtained with the non-catalytic run. All tested catalysts have negative effect on bio-oil yields. The bio-oil yields generally decreased with increasing the catalyst loadings. The deoxygenation degree in bio-oils changed depending on the type of catalyst and loading. A high degree of de-oxygenation took place with Mg(ClO4)(2) catalysts. An increased catalyst loading led to decreased aromatic contents of bio-oils catalysed by either Mg(ClO4)(2) or HClO4. The use of a catalyst increased total naphtha fractions in bio-oils. The highest heating value of the bio-oil was estimated to be approximately 30 MJ/kg. Gas chromatography-mass spectrometry analysis revealed that the bio-oils from the non-catalytic and catalytic runs contained aldehydes, ketones, phenols, acids, esters and alcohols. The relative yields of the oxygenated compounds were affected by catalyst type.Öğe Use of a Lewis acid, a Bronsted acid, and their binary mixtures for the liquefaction of lignocellulose by supercritical ethanol processing(Royal Soc Chemistry, 2021) Alper, Koray; Wang, Yun-Yan; Meng, Xianzhi; Tekin, Kubilay; Karagoz, Selhan; Ragauskas, Arthur J.Supercritical ethanol liquefaction of teak wood was carried out at 300 degrees C for 30 min without and with the use of Mg(ClO4)(2), HClO4, and HClO4/Mg(ClO4)(2) at various loadings (2-10 mmol). The bio-oil yield from the non-catalytic supercritical ethanol liquefaction of teak wood was similar to 41 wt%. The highest bio-oil yield (similar to 58.2 wt%) was obtained with the catalytic run using 2 mmol of Mg(ClO4)(2). In the catalyzed trials, with the use of either Mg(ClO4)(2) or HClO4, an increase in catalyst amounts resulted in a decrease in bio-oil yields. There was no clear trend for the use of co-catalysts. A degree of de-oxygenation was observed with the use of the catalysts studied. The O/C atomic ratio of the bio-oil from the non-catalytic was 0.44. The O/C atomic ratios in the bio-oil produced from catalytic runs ranged from 0.25 to 0.38. In the bio-oil from the non-catalytic run, the major compound was phenolic species, whereas esters were dominant in the bio-oils from the catalytic runs. The type of catalyst and its amount had significant effects on the product distributions and compositions. The prominent ester compounds were ethyl lactate and ethyl levulinate. The highest relative yield of ethyl levulinate was 49.1% and obtained with the use of the Mg(ClO4)(2)/HClO4 (2 mmol : 10 mmol) catalyst. The heating values of the bio-oils from catalytic runs were higher than that of the non-catalytic run. The highest heating value of 31.21 MJ kg(-1) was obtained with the Mg(ClO4)(2)/HClO4 (2 mmol : 10 mmol) catalyst.
