Christians believe in crucifixion of Jesus (Alaihi As-Salaam). We Muslims believe that Allah took him from this world. Could you please let me know where exactly in Qur'an it is mentioned about disappearance of Jesus (Alaihi As-Salaam) and his reappearance.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Allah refuted the claims of Jews that they kill 'Isa (Jesus) (Alaihi As-Salam). Allah Says (interpretation of meaning): {And because of their saying (in boast), "We killed Messiah 'Isa (Jesus), son of Maryam (Mary), the Messenger of Allâh," - but they killed him not, nor crucified him, but the resemblance of 'Isa (Jesus) was put over another man (and they killed that man), and those who differ therein are full of doubts. They have no (certain) knowledge, they follow nothing but conjecture. For surely; they killed him not [i.e. 'Isa (Jesus), son of Maryam (Mary). But Allâh raised him ['Isa (Jesus)] up (with his body and soul) unto Himself (and he is in the heavens). And Allâh is Ever AllPowerful, All-Wise.} [4:157-158]
The verse "Those who differ therein are full of doubts" means that the companions of 'Isa themselves could not decide the end of 'Isa . So, some of them believe according to the reality that he is only Allah's slave and His Messenger. Only the people of this opinion are on the truth and all other claims are nothing but misconceptions. Centuries later Christians in their zeal exaggerated in their worship and made him the "Son of God" while some of them made him "God a Himself" and others believe that he is the "Third of the three (Trinity)". High is Allah! From the great falsehood that they say. The evidence that 'Isa will descend again is the verse in which Allah Says (interpretation of meaning): {And there is none of the people of the Scripture (Jews and Christians), but must believe in him ['Isa (Jesus), son of Maryam (Mary), as only a Messenger of Allâh and a human being], before his ['Isa (Jesus) or a Jew's or a Christian's] death (at the time of the appearance of the angel of death). And on the Day of Resurrection, he ['Isa (Jesus)] will be a witness against them.} [4:159].
Imam Qatadah , Ibn Zaid said that the above verse means that everyone from the people of the book who will be alive before the Day of Judgment will believe in Iesa (Jesus) when he will come back. This opinion is also supported by the Imam the great Mufassir Ibn Jareer and Imam Ibn Katheer as well.
Allah knows best.