Brown coal tar hydrotreatment

Journal of Analytical and Applied Pyrolysis 89 (2010) 265–270 Contents lists available at ScienceDirect Journal of Analytical and Applied Pyrolysis journa l homepage: www.e lsev ier .co Brown Marcela Brown Coal Res a r t i c l Article history: Received 8 Ap Accepted 17 S Available onlin Keywords: Pyrolysis of co Coal tar Tar hydrotreat Hydrotreatme Catalyst labora n coa press drotre sente orth the f d the used 1. Introdu Through deprived at and 900 ◦C is the most important one. At high activation temperatures and employing proper activation medium, materials with extensive system of pores can be prepared from the semi-coke, which mate- rials can be used in the area of environmental protection as adsorbents [1,5,21,29–32]. Utilisation of such carbon-based mate- rials in this of various t separation [3,28,33,36 considerabl cal properti of the pores pyrolysis al and pyroge can serve a arrive at m hydrogenat employing Within t of Physical– ing and Use ∗ Correspon E-mail ad andel@vuhu.c ian R isati sis) [ roce mixtu are suitable for further industrial use; in particular in the area of propulsion fuels and their derivates. The envisaged outcome of the research of the properties of brown-coal-based mass consists in enhancement of knowledge on the brown coal tar, its qualitative properties in relation to the typeof the rawmaterial used, acquiring 0165-2370/$ – doi:10.1016/j. area varies very much: from treatment/purification ypes of wastewater streams, purification of flue gas, of permanent gases or capture of carbon dioxide –39]. The manner of use of these adsorbents depends y on the properties of these materials, whilst the criti- es are the specific surface area, distribution and shapes and the bulk weight [36]. Besides gas, the brown coal so generates liquid products; namely brown coal tar netic water [31]. The brown coal tar is a product that s appropriate raw material for ensuing processing to uch more noble products, such as motor fuels and oil es, which are currently produced mainly from crude oil multiple technological processes. he MSM 4456918101 research project titled “Research Chemical Properties of Materials Associated with Min- of Coal and their Environmental Effects in the North ding author. Tel.: +420 476208704; fax: +420 476208702. dresses: safarova@vuhu.cz (M. Sˇafárˇová), kusy@vuhu.cz (J. Kusy´), z (L. Andeˇl). information on prospective technological procedures and process condition needed for its splitting, including knowledge on the qual- ity of the products and the options of their hydrotreatment relying on the use of modern catalysts [26,40]. 2. Coal hydrotreatment Hydrotreatment processes belong to the group of processes of direct liquefying of coal mass; i.e. the processes by which coal are converted to liquid products. During these processes hydrogen is applied on the coal mass; either directly, in gaseous phase, or via so called H-donor solvent. In simplified terms the liquefying process can be described by the following equation: C + 0.8H2 = (CH1.6)n The hydrogen applied on the coal mass partly reduces sulphur and nitrogen contained in the coal, whereby the process also enables their easier removal from the fuel. At the same time ash content is also removed. The objective of the coal liquefying processes is pro- duction of fuel oil, diesel and naphtha from coal (which products have predominantly been produced from crude oil). On industrial see front matter © 2010 Elsevier B.V. All rights reserved. jaap.2010.09.002 coal tar hydrotreatment Sˇafárˇová, Jaroslav Kusy´, Lukásˇ Andeˇl ∗ earch Institute, j.s.c., Budovatelu˚ 2830, 43437 Most, Czech Republic e i n f o ril 2010 eptember 2010 e 25 September 2010 al ment nt reactor a b s t r a c t The paper dealswith the outcomes of inwhich tarwas a by-product of brow tor at 300 ◦C and at varied operational coal tar samples earmarked for the hy of brown coal, in which samples repre be found in individual districts of the N parameters were determined both of (gaseous, water and organic phases an on the operational hydrogen pressure ction pyrolysis of solid carbon-based materials at air- mosphere and at temperatures ranging between 600 multiple products are generated, of which semi-coke Bohem on util pyroly such p noble m/locate / jaap tory experiments concerning brown coal tar hydrotreatment, l pyrolysis. The experimentswere carried out in pressure reac- ures of hydrogenused as hydrotreatmentmedium. The brown atment tests had been prepared through pyrolysis of samples d, in terms of qualitative parameters, the brown coal types to Bohemian Coal Basin. During the experiments the qualitative eed material (brown coal tar) and of the products generated hydrotreatment residue). The yields of these products as per during the hydrotreatment process were also determined. © 2010 Elsevier B.V. All rights reserved. egion”, in recent years research has also been focused on of brown coal tar (liquid product of coal material 34]. On the basis of multiple experiments carried out, dures have been employed that enable to generate a re of hydrocarbons from the tar, which hydrocarbons 266 M. Sˇafárˇová et al. / Journal of Analytical and Applied Pyrolysis 89 (2010) 265–270 Nomenclature Symbols and abbreviations TSKd WSKd GSKd SKd scale, the te ticular befo multiple fa technology in Leuna (Be tion of Czec coal was als operated un In the se of motor fu nologies, as crude oil su and its risin developed in a pilot sc prognoses s crude oil in As far as priate coal (brown coa groups (vitr and genera completely compositio fying techn The follo direct lique • Pyrolysis: ture exce evaporate of liquid process g hydrogen are used, liquefying process (G • Hydro-py 870 ◦C) in are used pyrolysis COED (US • Hydrotrea ature of a 20MPa) i is employ of this pro • Solvent ex much as 4 environm whilst no given as a • Extraction toluene o from the tures and pressures that are higher than the critical temperature and the critical pressure of the relevant solvent are. The NCB (Great Britain) process is an example of this technology [4]. the sitio arbo cal tr arbo oces the her hydr prod e de ,14] ted i , nam ond and rproc l or erim obje , the he py Bohe ts, in ying exp ssibi s con ratio qual rude bro ut in , inle f cob ercia % of C e is A m i teria chos raw tical nera epar reatm the h coal hich tar content (converted to dry condition) pyrogenetic water content (converted to dry condi- tion) gas content (converted to dry condition) semi-coke content (converted to dry condition) chnologies of liquefying of coal had been used in par- re and during the World War II in Germany, where cilities of the kind had been operated [2,26]. The first of direct liquefying had been made operational in 1927 rgius Process – IG Farben). During the German occupa- hoslovakia an industrial complex for liquefying brown o built in the Záluzˇí u Litvínova village, which had been til the mid-1960s. cond half of the 20th century the process of production els from crude oil was gradually replacing these tech- crude oil was a cheaper feed material. Due to multiple pply crises, decreasing amounts of available crude oil gprices, the technologiesof coal liquefyingare currently intensively. Multiple facilities of the kind are operated ale particularly in Europe and the USA. Moreover, the uggest that coalwill be one of the fuels thatwill replace future [2,12,35]. the liquefyingprocesses are concerned, themost appro- is such coal that contains high amount of hydrogen l and lignite) and high amounts of reactive maceral inite and exinite). Hard coal is more difficult to liquefy tes lower yields of liquid products, whilst anthracite is unsuitable for the liquefying process. The yields and the n of liquid products depend mainly on the used lique- ology, type of coal and selected reaction conditions. wing procedures are the basic types of the processes of fying of coal: In air-deprived atmosphere coal is heated to tempera- eding 500 ◦C, whereby volatile flammable material is d, which, after cooling down, emerges as a mixture and gaseous products. Of all the other processes this enerates the lowest yields of liquid products and no is supplied from an external source and no catalysts nor is increased pressure applied. This is not a typical process as coke is themainproduct. The Lurgi–Ruhrgas ermany) may serve as an example [20,25]. rolysis: Coal is heated to high temperature (as much as the gaseous hydrogen environment,whilst no catalysts or increased pressure applied. In comparison with the process the yields of liquid products are higher [41]. The A) processmay serve as an example of this process [13]. tment liquefying: Coal paste is heated to the temper- s much as 450 ◦C at increased pressure (as much as n the environment of gaseous hydrogen and a catalyst ed. The H-Coal (USA) process may serve as an example cess [15,16]. traction: The coal paste is heated to temperature as All compo hydroc nologi hydroc tant pr out by alyst, w As the liquid mixtur too [11 separa ranges corresp range) furthe therma 3. Exp The ditions from t North produc emplo The the po carbon at gene whose from c The ried o 300 ◦C ence o (comm 1.5wt. balanc and 8m the ma it was in the the cri test-ge 3.1. Pr hydrot For brown unit, w 50 ◦C at increased pressure (as much as 15MPa) in the ent of H-donor solvent (hydrogen transfer medium), catalysts are used. The EXXON (USA) process can be n example [22]. in above-critical conditions: Ordinary solvents, such as r water, are used for separation of liquid hydrocarbons coal mass. The extraction takes place at such tempera- that brown For the pur coal tar, sa coal in the from theNo Coal Basin ( Mine Nástu above processes generate liquid products of various ns, whilst these products are very rich mixtures of ns. These mixtures must be subjected to further tech- eatment, which will enable splitting these mixtures to n cuts as per the boiling point ranges. The most impor- ses include hydrotreatment splitting, which is carried addition of hydrogen in the presence of a suitable cat- eby the C:H ratio changes in the hydrocarbon mixture. ogen content grows in the hydrotreatment-generated uct, the molecular weight of the components of the creases and, hence, the boiling points of the products . Afterwards, the emerged liquid product is distillation- nto individual distillation cuts as per the boiling point ely to naphtha cut (boiling pointwithin 200 ◦C), the cut ing todiesel (virgindiesel) (the200–360 ◦Cboilingpoint the cut with boiling point above 400 ◦C, which could be essedemployingother splittingprocesses (visbreaking, catalytic cracking). ental ctiveof theexperimentswas toapply, in laboratory con- procedure of hydrotreatment splitting of tar originating rolysis of brown coal mined in individual mines of the mian Brown Coal Basin and to check the quality of the particular in terms of prospective further processing other technologies. eriments carried out were focussed on verification of lity of hydrotreatment splitting of polynuclear hydro- tained in brown coal tars employing modern catalysts nofhydrocarboncutswithboilingpointswithin400 ◦C, ity is close to the quality of naphtha anddiesel produced oil. wn coal tar hydrotreatment experiments were car- hydrotreatment pressure reactor at temperature of t hydrogen pressure of 0.1–3MPa and in the pres- alt–molybdenum-based catalyst deposited on alumina l code: BASF 0852). Composition of Co–Mo catalyst is oO, 11wt.% of MoO3 and 5wt.% of TiO2 (the rest to the l2O3 as a carrier), the particle size is 3mm in diameter n length. This catalyst is suitable for hydrotreatment of ls with the content of organic sulphur compounds, so en due to the relatively high amount of total sulphur material (0.24wt.%) [40]. During these experiments all qualitative parameters of both input raw materials and ted products were determined. ation of blended samples of brown coal tar for the ent tests ydrotreatment tests a blended sample was prepared of tar by pyrolysis of brown coal in a laboratory pyrolysis is provided with a retort of volume of some 2.5 L, so coal batch of weight of some 1000g can be processed. pose of preparation of the blended sample of brown mples had been taken of all routinely mined types of Czech Republic. They included samples of brown coal rth Bohemian BrownCoal Basin and the Sokolov Brown frommines titled as follows: Centrum, CˇSA,Mine Bílina, p Tusˇimice and Mine Jirˇí). M. Sˇafárˇová et al. / Journal of Analytical and Applied Pyrolysis 89 (2010) 265–270 267 Table 1 The results of determination of the yields of tar, water, gas and coke residue at low temperature distillation of brown coal samples. Sample code TSKd (%) SKd (%) WSKd (%) GSKd (%) Mine Centrum 16.54 63.44 9.21 10.81 Mine CˇSA 19.27 63.45 8.07 9.21 Mine Bílina 14.62 65.89 8.57 10.92 Mine DNT 7.01 68.79 9.77 14.43 Mine Jirˇí 18.12 64.51 8.29 9.08 The brown coal batch of weight of 1000g was put into the retort of the laboratory pyrolysis unit and was subjected to pyrolysis (the temperature reached 650 ◦C). The yields of the products were determined by laboratory carbonisation tests [6], whose results are given in Table 1. By pyrolysis of individual batches of brown coal from different mines partial samples of brown coal tar were obtained, from which blended sample of overall volume of some 1000ml was prepared by homogenisation. This blended sample of thebrowncoal tarwas the feedmaterial for theensuinghydrotreat- ment tests. Before execution of the tar hydrotreatment splitting experiments themselves, the basic analyses of the tar had been car- ried out, which had included determination of kinematic viscosity at 40 ◦C [7], specific gravity [8], flash point as per Pensky Martens [9], sulphur content [10], water content (distillation method with xylene) as well as identification of organic substances employ- ing gas chromatography (GC) +detection by flame-ionisation mass detector (FID/MS). The results of the determination of the basic qualitative param- eters of the blended samples of the brown coal tar are given in Table 2 The results of determination of qualitative parameters of blended sample of tar. Parameter Specific gravity (kgm−3) 953.56 Flashpoint in closed cup (◦C) 0.5 Water content – distillation (xylene) (%) 2.86 Sulphur content (%) 0.24 Carbon content (%) 78.83 Hydrogen content (%) 9.90 Nitrogen content (%) 0.51 Table 2. Employing the GC FIT/MS methodology more than 500 species of organic substances was discovered, of which phenols, toluene, benzene and its derivates and xylene formed the best part. The blended sample of brown coal tar prepared by the above procedure was used for ensuing hydrotreatment tests. In terms of qualitative parameters this sample is an average sample of tar pre- pared by pyrolysis of brown coal originating from the districts of the North Bohemian Coal Basin. 3.2. Hydrotreatment tests The hydrotreatment tests were carried out in hydrotreatment reactormade by PARR company,model 4520,whichwas controlled by a control unit (model 4843), as can be seen in Fig. 1. The reac- tor is provided with pressure vessel of 1000ml volume, to which a basket with catalyst is installed as well as a stirrer (see Fig. 2). The maximum operating pressure and temperature of the reactor are 13MPa and 350 ◦C, respectively, with the option to introduce Fig. 1. The PARR hydrotreatment reactor, model 4520, and the control unit. 268 M. Sˇafárˇová et al. / Journal of Analytical and Applied Pyrolysis 89 (2010) 265–270 Fig. 2. Catalyst-accommodating basket, stirrer and catalyst BASF 0852. hydrogen gas up to the pressure of 4MPa. The design of the reac- tor is such that it can be purged with inert gas (nitrogen) and it is also possible to introduce into it liquid organic phase—up to the maximum operational pressure of 10MPa. The equipment is pro- vided with water-cooled condensation loop to enable separation of the liquid phase generated by the hydrotreatment processes in the reactor. Cobalt–molybdenum hydrotreatment catalyst on alumina carrier was chosen for testing the hydrotreatment processes—due to its capability to hydrotreat sulphur compounds present in the brown coal tar to sulphane as per the following reactions [17]: RSH + H2 ⇔ The hydrotr perature of (correspond respectively ment in the Each hy pressure in gas was int ment, wher were collec were separ [18] for the raphy (GC) compositio Fig. 3. The catalyst and the hydrotreatment products generated at the operating pressure of 5Mpa. arated organic phase was deprived of dust impurities employing filtration through glass wool and the residual water was removed using water-free sodium sulphate. The operational conditions were identical for all the executed hydrotreatment tests and what was only changed was the oper- ating pressure (5, 6.5 and 8MPa). With all the tests carried out, the weight of the emerged products was recorded; i.e. water and organic phases and hydrotreatment residue so that the hydrotreat- est y tativ ssure vesse prod was . On ered weig r pres hyd show each tar h drot occu was Graph 1. RH + H2SandR2S + 2H2 ⇔ 2RH + H2S eatment testswere carried out at the basic reactor tem- 300 ◦C and operating pressures of 5, 6.5 and 8MPa ing to inlet hydrogen pressure of 0.1, 1 and 3MPa, ). Some 150ml of blended tar was used for hydrotreat- reactor for each test. drotreatment test was discontinued after the steady the reactor had lasted 1h and the reaction-generated roduced via capillary tube to the condensation equip- e it was cooled down. The condensed liquid products ted and water and organic phases of these products ated. During the tests the gaseous phase was sampled purpose of ensuing analysis employing gas chromatog- and thermal-conductivity detector (TCD) so that the n of the emerging gas might be determined. The sep- ment t quanti tor pre of the of this basket iments discov which reacto ing the tar are For by the and hy nents phase Simulated distillation curve of the liquid organic phase generated during hydrotreatmen ieldsmight be determined. Therewere difficulties about e transfer of the hydrotreatment residue from the reac- vessel as, due to its high density, it stuck onto thewalls l and on the catalyst surface, which caused some losses uct. That is why the weight of the catalyst-containing determinedbefore the experiments and after the exper- the basis of this weight differential the amount was of the hydrotreatment residue stuck on the catalyst, by ht the weight of the product taken directly from the sure vesselwas increased. The products generated dur- rotreatment tests of the blended samples of brown coal n in Fig. 3. test analyseswerecarriedoutof theproductsgenerated ydrotreatment; i.e. liquid organic phase, reaction water reatment residue. Identification of individual compo- rring in the reaction water and in the liquid organic carried out employing the GC-FID/MS method. At the t of brown coal tar at different hydrogen operational pressures. M. Sˇafárˇová et al. / Journal of Analytical and Applied Pyrolysis 89 (2010) 265–270 269 Graph2. Yield sures o catalyst (Notes same time, mined for method. 4. The resu For evalu of brown co generated a operating p determined the graph t distillation The ana tained some by weight o of sulphur a the tests ca in the hydr rising opera content in t pressure of content in t with its con Employi organic spe during the their deriva naphthalen tar, concent eral factors tar hydrotre of xylene an parison wit in the orga Phenol met in both the the tar, the alkyl deriva double. Employi identified in nols and the in particula com rotr show d8% the cha e di reatm 8M l pre s. Th f liq f the clus yrol air-f – be tar is and e the oduc mix le te we s of individual components generatedduringbrowncoal tar hydrotreatment at pres : OF – liquid organic phase; HZ – hydrotreatment residue). distillation curve of the liquid orga