Obtaining of Furfural from Hardwood Residues, Keeping Lignocellulose for Production of Activated Carbon

Woodworking industry residues often do not find proper utilisation and are heaping up or used as a fuel at best. One of the feasibilities of the appropriate use of this out-of-demand but yet valuable raw material is to produce furfural, acetic acid and activated carbon. Since such a unified processing scheme is almost unexplored, our intention was to study the main parameters of the process. Birch wood veneer shorts were chosen as a starting raw material. It contained 72.2% polysaccharides, including 29.9% of easy-hydrolysable polysaccharides; the potential fufural yield was 15.3% on the o.d. wood basis. Therefore, the impact of the catalyst (concentrated sulphuric acid) was studied to elucidate the optimum conditions to ensure a high yield of furfural and lignocellulose with appropriate properties for obtaining of the activated carbon. Changing the amount of the catalyst, the furfural and lignocellulose yields varied from 6.3 to 8.9% and from 70.9 to 60.3% on the o.d. wood basis, respectively. Furfural and acetic acid are obtained by catalytic prehydrolysis of hardwood residues; 2/3 of the left-over lignocellulose is used as a fuel in a boiler house and the rest 1/3 as a raw material for carbon production. The novel technology of processing fine-grained hardwood residues is environmentally friendly and energetically self-sufficien

Furfurola un etiķskābes iegūšana bērza koksnes priekšapstrādes procesā

Ievadā ir pamatota promocijas darba aktualitāte, formulēts mērķis un uzdevumi, kā arī izklāstītas promocijas darba pamatnostādnes. Pirmā nodaļa ir veltīta literatūras apskatam, kurā ir izskatīta iespēja iegūt bioetanolu no lignocelulozi saturošām izejvielām (koksnes, salmiem, sēnalām u.c.), kā arī izskatīti biomasas priekšapstrādes procesi. Apkopota un izanalizēta literatūra par furfurola, etiķskābes un bioetanola iegūšanas, pielietošanas iespējām. Aprakstīta bioetanola iegūšanas no koksnes vēsturiskā attīstība, patēriņi un izejvielas. Otrā nodaļa veltīta eksperimentālajai daļai, kurā pamatota izejvielas izvēle, kā arī izejmateriāla un lignocelulozes ķīmiskā sastāva noteikšanā izmantotā metodika, (sk. 3. att.), pilotiekārtas un darba metodikas ar tām. Promocijas darba eksperimentālās daļas veikšanai esmu izvēlējies bērza koksni, kura aizņem 30% no teritorijas mežiem un ir labs celulozes un hemiceluložu izejmateriāla avots. Promocijas darbā jaunās tehnoloģijas izstrādāšanai izmantota shēma, kas parādīta 4. attēlā. Trešajā nodaļā ir rezultāti un to izvērtējums. Noteikts bērza koksnes ķīmiskais sastāvas, priekšapstrādes procesa pētījumi par pentozānu deacetilēšanu iegūstot etiķskābi, un pentozānu hidrolīzi un pentožu dehidratāciju iegūstot furfurolu pie temperatūrām (137°C, 147°C, 157°C un 167°C), sērskābes koncentrācijās (3%, 6% un 9%) un laika ietekmes rezultātā (10-120 min), kā arī glikozes šķīduma iegūšanas izpēte, izmantojot skābo un enzimātisko hidrolīzi. Vēl trešajā nodaļā pētīta bioetanola iegūšana, un aprēķināta iespējamā peļņa rūpnieciski realizējot promocijas darbā iegūtos rezultātus. Secinājumos ir formulēti sasniegtie darba rezultāti, un definēti būtiskākie atzinumi. Literatūras sarakstā ir uzskaitīti darbā izmantotie literatūras avoti

Deacetylation of Alder Wood Hemicelluloses Depending on the Catalyst Amount

The world’s consumption of acetic acid has increased from 6.7 million t in 2002 up to 7.9 million t in 2007 and continues to grow. Besides, the production technology of this product has changed dramatically. Some years ago, when the oil price was lower, acetic acid was produced from ethanol by way of fermentation. Still now 75% of commercially used acetic acid is produced from methanol by the catalytic process. Acetic acid is currently produced by 165 companies, and its major quantity is used for producing vinyl acetate monomer. In connection with the oil price increase, it can be forecasted that it will be necessary to produce acetic acid as well as other chemical products from biomass. Therefore, our studies in this direction become increasingly urgent. To develop the theoretical foundations for the new technology, it is necessary to investigate the effect of the main parameters on the wood hemicelluloses deacetylation process. In the present work, the effect of the catalyst amount on the alder wood hemicelluloses polysaccharides deacetylation process is investigated. The studies were carried out, treating the raw material in the presence of a catalyst with steam in an original pilot plant, with the main reactor’s volume 13,7 l and height 1450 mm. This pilot plant makes it possible to model an industrial process. Kinetic studies have shown that the alder wood hemicelluloses polysaccharides deacetylation reaction rate constant has decreased during the process. For example, at the temperature 430 K and the catalyst amount 1.0% from dry wood, the hemicelluloses deacetylation reaction rate constant has decreased from 2.14 • 10-2 min-1 to 1.41 • 10-2 min-1 during the process. This is explained by the fact that the acetyl groups in the hemicellulose polysaccharide macromolecule are linked variously and unevenly. The acetic acid yield from alder wood, with increasing catalyst amount from 1.0% to 2.0% from dry wood, grows from 57.0% to 80.2% from the theoretically possible one, respectively. To increase this yield still more, it is envisaged to study the effect of temperature on the hemicelluloses polysaccharides deacetylation process

Influence of the Catalyst Amount on the Kinetics of Acetic Acid Formation from Wheat Straw

The growth of petroleum prices on the world’s market within the recent years has raised the cost of synthetic chemical products and, respectively, has enhanced the competitiveness of the products, including also acetic acid, which can be obtained from plant biomass. Acetic acid is currently produced mainly by way of fermentation of alcohol-containing solutions, and only a small part is obtained from wood dry distillation products. However, already in the immediate future, owing to the new state of the art in the petroleum market, the overall production of furfural and acetic acid applying the hydrolysis technology, will grow. Therefore, all studies along these lines, including also acetic acid formation from straw, become increasingly urgent, since this raw material is formed in great quantities worldwide, and it has not yet found regular utilization. In the present work, the kinetics of the formation of acetic acid from wheat straw was investigated. The obtained data can be used to develop a new technology for obtaining acetic acid

Furfural and Bioethanol Production from Hardwood and Agricultural Waste

In the near future hardwood may be a real alternative to oil as a raw material for production of chemicals and motor fuel. A new approach to solve this problem has been found. The aimed change of the mechanism of the process has permitted to solve two problems simultaneously: to increase the furfural yield from 55% up to 75% from the theoretical yield And to diminish 7 times the degree of cellulose destruction. On the basis of theoretical studies, a new technology including two-step hydrolysis of hardwood and other pentosan-containing raw material has been developed. Since 1997, for the first time in the world's industrial practice, this technology of yielding furfural and bioethanol has been realized in Russia with the annualy capacity of 4.300 t furfural and 11 million l bioethanol. The degree of raw material utilization has grown 3 times compared to furfural production alone

Analytical Control of the Process of Preparing Lignocellulose for Obtaining Levoglucosan

The yield of the main product of the thermal destruction of cellulose - 1,6-anhydro-β,D-glucopyranose or levoglucosan (LG) in the fast thermolysis of hardwood increases several times, if pre-hydrolysis of wood in the presence of a sulphuric acid catalyst at the temperature 150 -155°C is carried out, thereby achieving the hydrolysis of the main part of hemicelluloses. The lignocellulose (LC) obtained after washing are also the LG raw material. In the study, the chemical composition of the intermediate products formed in the technological process of preparing LC as well as the degree of polymerisation (DP) of cellulose in wood and the obtained LC are investigated. A possible correlation between the DP and the LG yield is discussed. The component composition is determined, and the applicability and purification potentialities of the obtained intermediate products – prehydrolysis condensates and LC washing waters are evaluated. The pre-hydrolysis process condensate contains a considerable amount of acetic acid and furfural, namely, 5% and 12% from the oven dry wood mass, respectively. The obtained LC chips are washed with water till the pH 2.0-2.2 or the H2SO4 concentration from oven dry LC about 0.1% from its mass. 19-21% of oven dry wood organic substances, from which 78-88% are monosaccharides, are diluted in the washing waters. After the washing, the LC yield is 52-55% in terms of oven dry wood. During the pre-hydrolysis, as a result of the action of sulphuric acid and elevated temperature, the DP of cellulose decreased from 1800-1900 in alder wood to 1200-1400 in LC. Comparing the LG yields from Kuerschner cellulose preparations prepared from the initial wood and LC, a considerably higher LG yield is obtained from the latter. The thermolysis with the corresponding wood and LC samples, carried out in parallel, has shown that the acid-treated material (LC) demonstrated considerably higher LG yields, which, taking into account the cellulose content in LC (45-55%), actually correspond to the LG yield from the corresponding Kuerschner cellulose preparation. The use of the condensate for obtaining furfural and acetic acid is technically feasible. The applicability of the LC washing waters is still under study, although they do not present any problems in the wastewater biological treatment facilities

Bioetanola un furfurola kopēja iegūšana no lapkoku koksnes

Naftas cenu celšanos pasaules tirgū pēdējos gados sadārdzināja sintētiskās ķīmijas produkciju un attiecīgi pacēla konkurētspēju produktiem, kurus var iegūt no augu biomasas, tajā skaitā arī etanolu un furfurolu. Pasaulē bioetanola ražošana ik gadus palielinās par 10%. Tagad etanolu ražo, galvenokārt, sintētiski vai arī fermentējot. Bet jau tuvākajā nākotnē, sakarā ar jaunu situāciju naftas tirgū, palielināsies furfurola un bioetanola kopēja ražošana, izmantojot hidrolīzes tehnoloģiju. Tāpēc visi pētījumi šajā virzienā paliek arvien aktuālāk, tajā skaitā arī furfurola un bioetanola iegūšana no lapkoku koksnes, jo šī izejviela ik gadu rodas pasaulē lielā daudzumā. Šinī darbā mums ir izpētīta furfurola veidošanās dinamika un kinētika no bērza koksnes atliekām, saglabājot celulozi tālākai pārstrādei – bioetanola iegūšanai. Iegūtie rezultāti var būt izmantoti furfurola un bioetanola iegūšanas jaunas tehnoloģijas izstrādāšanai

Bioethanol Production from Hardwood and Agricultural Waste

In the near future foliage wood may be as a real alternative to oil as raw material for production of chemicals and motor fuel. A new approach to solve this problem consisting of differential catalysis of hydrolysis and dehydration reactions has been found. The aimed change of the mechanism of the process has permitted to solve two problems simultaneously: to make increase the furfural yield from 55% up to 75% from theoretical and to diminish 5 times degree of the cellulose destruction. On the basis of theoretical studies a new technology including two-step hydrolysis of foliage wood and other pentosan containing raw material has been elaborated. Since 1997 for the first time in the world's industrial practice this technology yielding furfural and fermentable sugars further processed into bioethanol has been realized in Russia with capacity 4.300 t/a of furfural and 8.800 t/a of bioethanol. The degree of raw material utilization has grown 3 times, the total yield of furfural and fermentable sugars - 4 times when compared to the only furfural production

The Effect of Catalyst Amount on the Production of Furfural and Acetic Acid from Birch Wood in the Biomass Pretreatment Process

The conversion of lignocellulosic biomass to bioethanol has attracted renewed attention in recent years due to its environmental, economic, and strategic advantages. Birch woodchips were used as the raw material due its several characteristics, such as high cellulose and hemicellulose content that can be readily hydrolyzed into fermentable sugars. Dilute acid hydrolysis was used as the pretreatment process which can be considered as one of the most promising biomass pretreatment methods. But there occur several challenges and limitations in the process of converting birch wood to bioethanol. During the biomass pretreatment process the degradation products such as furfural and acetic acid, which has an inhibitory effect on the further fermentation process in the bioethanol production section, may be form from hemicelluloses. But both these inhibitors as individual chemicals are very important for the production of many products. In order to develop the theoretical foundations for joint production technology of furfural, acetic acid and bioethanol, it is necessary to study the effect of the amount of catalyst on the formation of furfural and acetic acid from birch woodchips and the content of cellulose in the lignocellulose residue after pretreatment process. The effect of the amount of the catalyst on the furfural and acetic acid formation process was studied in a range from 1.5% to 4.0%, calculated on oven dried wood (o.d.w.), while temperature and time of the pretreatment process were constant. The obtained results demonstrated that the effect of the amount of the catalyst on the formation of furfural and acetic acid and the content of cellulose in the lignocellulosic leftover is very significant. The amount of furfural increased from 6.2 % to 10.8%, calculated on o.d.w., the amount of acetic acid increased from 5.2% to 5.8%, calculated on o.d.w., but the content of cellulose in the lignocellulosic leftover decreased from 34.7% to 14.1%, calculated on o.d.w. after 90 min from the beginning of the birch wood pretreatment process

Levoglikozāna iegūšanas procesa analītiska kontrole

Celulozes termiskās noārdīšanas galvenā produkta 1,6-anhidro-β,D-glikopiranozes jeb levoglikozāna – (LG) iznākums lapukoku koksnes ātrajā termolīzē daudzkārt palielinās, ja veic koksnes priekšhidrolīzi sērskābes katalizatora klātbūtnē 150-155°C temperatūrā, ar ko panāk hemiceluložu hidrolīzi. Pēc skalošanas iegūtā lignoceluloze (LC) tad arī ir LG izejviela. Darbā pētīts LC pagatavošanas tehnoloģiskajā procesā radušos starpproduktu ķīmiskais sastāvs un celulozes polimerizācijas pakāpe (PP) koksnē un iegūtajā LC. Apspriesta celulozes PP un LG iznākuma iespējamā korelācija. Noteikts komponentu sastāvs un novērtētas iegūto starpproduktu – priekšhidrolīzes kondensātu un LC skalošanas ūdeņu izmantošanas un attīrīšanas iespējas. Priekšhidrolīzes procesa kondensāts satur ievērojamu daudzumu vērtīgās etiķskābes un furfurola – attiecīgi 5% un 12% no absolūti sausas koksnes masas. Pāri palikušo LC skalo ar ūdeni līdz pH 2,0-2,2 jeb H2SO4 koncentrācijas absolūti sausā CL ap 0,1% no tā masas. Skalošanas ūdeņos izšķīst 19-21% no absolūti sausas koksnes organisko vielu no kurām 78-88% sastāda monosaharīdi. Pēc skalošanas LC iznākums ir 52-55%, rēķinot no absolūti sausas koksnes. Priekšhidrolīzes laikā sērskābes un paaugstinātas temperatūras iedarbības rezultātā celulozes PP no 1800-1900 alkšņa koksnē pazeminājās līdz 1200-1400 LC. Salīdzinot LG iznākumus no Kiršnera celulozes preparātiem, kas pagatavoti no izejas koksnes un LC, ievērojami augstāks LG iznākums iegūts no pēdējā. Paralēli veiktās termolīzes ar atbilstošās koksnes un CL paraugiem parādīja, ka ar skābi apstrādātais materiāls uzrādīja daudz augstākus LG iznākumus, kuri, ņemot vērā celulozes saturu LC (45-55%), faktiski atbilda LG iznākumam no atbilstošā Kiršnera celulozes preparāta. Kondensāta izmantošana furfurola un etiķskābes iegūšanai ir tehniski iespējama. LC skalošanas ūdeņu izmantošanas iespējas vēl tiek pētītas kaut arī notekūdeņu bioloģiskās attīrīšanas iekārtās tie sarežģījumus neradītu