Després de dinar, guardaré l'informe al despatx abans d'enviar-lo a la clienta.

Both are possible, but they mean slightly different things.

després de dinar uses de + infinitive and means after eating lunch / after having lunch. It focuses on the action.

després del dinar uses the noun el dinar and means after the lunch / after the meal. It focuses more on the event or meal as a thing.

Catalan often uses preposition + infinitive where English uses after + -ing:

• després de dinar = after having lunch
• abans de sortir = before leaving

guardaré is the future simple, first person singular: I will keep / I will put away / I will store.

It is formed from the infinitive guardar + the future ending -é.

So:

• guardar = to keep / store
• guardaré = I will keep / I will store

In Catalan, this simple future is very normal and natural, not especially formal.

Because the masculine singular article el becomes l' before a vowel sound.

So:

• el llibre = the book
• l'informe = the report
• l'home = the man

This is called elision. Catalan does this very regularly to avoid a clumsy vowel sequence.

Because al is the contraction of a + el.

• a = to / at / in
• el despatx = the office
• al despatx = to the office / in the office

Catalan makes this contraction automatically:

• a + el = al
• de + el = del

So guardaré l'informe al despatx uses the normal contracted form.

Usually no. despatx normally means office or study, not the piece of furniture.

If you mean desk as furniture, Catalan more often uses escriptori.

So here al despatx is most naturally understood as in/to the office, not on the desk.

Because after abans, Catalan normally uses de + infinitive.

So:

• abans d'enviar-lo = before sending it
• abans de sortir = before leaving
• abans de parlar = before speaking

Since enviar begins with a vowel, de becomes d':

• de enviar-lo → d'enviar-lo

This is the standard pattern: abans de + infinitive.

Because with an infinitive, Catalan usually attaches weak pronouns to the end of the verb with a hyphen.

So:

• enviar-lo = to send it
• veure-la = to see her / it
• fer-ho = to do it

Here -lo replaces l'informe.

This is different from many cases with a conjugated verb, where the pronoun usually goes before:

• L'enviaré = I will send it

But with the infinitive enviar, the normal form is enviar-lo.

-lo refers back to l'informe.

Since informe is a masculine singular noun, the matching direct-object pronoun is lo in this position.

So:

• l'informe → -lo

That is why Catalan avoids repeating the noun:

• abans d'enviar l'informe a la clienta
• abans d'enviar-lo a la clienta

The second version sounds more natural because it avoids repetition.

Because the client is the recipient of the report, and Catalan marks that with a.

So:

• enviar alguna cosa a algú = to send something to someone

Here:

• l'informe = the thing being sent
• a la clienta = the person receiving it

Also, clienta is the feminine form, so it means a female client/customer. If it were masculine, it would be:

• al client

They help show both stress and, in many cases, vowel quality.

• després is stressed on the last syllable
• guardaré is also stressed on the last syllable

The acute accent é tells you it is a closed e sound in standard Catalan.

So the accents are not optional spelling marks; they are an important part of correct written Catalan.

Yes, Catalan has some flexibility in word order, especially with time expressions like després de dinar and abans d'enviar-lo a la clienta.

The original sentence is very natural:

• Després de dinar, guardaré l'informe al despatx abans d'enviar-lo a la clienta.

But you could move things around for emphasis, for example:

• Guardaré l'informe al despatx després de dinar, abans d'enviar-lo a la clienta.

The original version sounds clear and well balanced, though, and is probably the best choice for a neutral statement.